Learn step by step how to make a smoked london broil on ANY grill or smoker! Whether you’ve got a Weber kettle, a propane gas grill, or even a Traeger pellet grill, we’ve got you covered.
Take this plain piece of beef to the next level by marinating overnight, smoking, and REVERSE SEARING this cut to perfection before resting and serving!
Let’s get started!
A london broil, sometimes called a flank steak, is not a particularly revered cut of beef in the fancy pants world of steaks.
But today, we are going to show you how to take this mild mannered cut of beef from Clark Kent to Superman status!
We are going to cover:
- How to prepare your london broil for the smoker with a good rub and marinade
- The best wood choices for a smoked london broil
- How to set up different grills and smokers for a smoked london broil
- What temperature to smoke your london broil
- How to reverse sear your smoked london broil for the most delicious flavor and texture.
- How to know precisely when your smoked london broil is finished
- How to rest, slice, and serve your perfect smoked london broil.
Wow, that’s a lot…so let’s jump in!
What is a London Broil?
Take a look at an anatomy chart of a steer, and you aren’t likely to see the term ‘London Broil” anywhere on it.
That’s because it actually comes from the Top Round section, which is found on the steer’s lower hind quarters, or “flank”, hence the term “flank steak” used interchangeably at times.
“London Broil” is simply a marketing term likely developed by some meat purveyor many years ago trying to sell some of his lesser desired cuts of beef to the wine and cheese crowd.
While you can technically broil a london broil start to finish, (like you can technically do with ANY type of steak), today we are going to have some fun and smoke this bad boy before we sear it.
How to Prepare a London Broil for the Smoker
Top Seasonings and Marinades for Smoked London Broil
Because london broil is so naturally lean and tough, along with being relatively thin, it benefits from a good marinade before cooking to keep it from drying out on the grill or smoker.
Generally this is done with a combination of oil and vinegar. We prefer about 1/4 cup vegetable oil and 2-3 Tbsp of either red wine vinegar or apple cider vinegar.
Whisk the oil and vinegar together and pour over the london broil in a wide and shallow baking dish before applying your steak rub to both sides.
If you are going for more traditional steak flavors, choose the red wine vinegar along with something like a Montreal Steak Seasoning.
If you are going for more of BBQ flavor, choose the apple cider vinegar and then rub the steak with something like Bad Byron’s Butt Rub.
We are big fans of this rub for steaks and beef because it contains no sugar, which can easily burn during the reverse searing portion of the cook.
Save your sugary rubs for the ribs and pork butts you will be smoking low and slow and less likely to burn.
Salt and Marinate Overnight
When you are preparing your london broil its best to season and marinate it at least 2 hours before smoking, preferably even overnight, before putting it on the smoker or grill.
This allows the rub and marinade time to penetrate the meat, ensuring you have flavorful steak all the way to the center and not just salty on the exterior, and bland in the middle.
Also, did you know that if the meat is fully salted throughout, it is chemically more able to hold onto is juices and retain more moisture during the cooking process?!
Hence why the boiling point of saltwater is higher than that of pure water.
We marinate the london broil for at least 2 hours, preferably overnight, covered in a glass baking dish.
This gives the salt loads of time to penetrate the meat and really flavor it all the way through.
Pro Tip: Don’t use aluminum baking pans or foil trays when working with vinegar marinades as the acid can interact with the metal and leave a sour taste on the meat. Stick with plastic or glass!
Best Smoking Wood Choices for a London Broil
For a big robust piece of beef like a smoked london broil, we’d recommend going with something like hickory or pecan that will stand out and also compliment the beef well.
If you want to keep it simple and straightforward, choose a lighter smoking wood like oak, apple, or peach, although these lighter fruitwoods may not impart as much smokey flavor into the beef as they will with chicken or fish.
And if you want that distinct mesquite flavor, well, go with mesquite.
You will only be smoking the london broil for about an hour so you don’t have to worry about overdoing it by choosing too strong of a smoking wood.
When in doubt, you can always mix and match your choices!
Best Times and Temperatures for Smoking a London Broil
You will need to watch both your cooking temperature and internal temperatures carefully when smoking the london broil.
We recommend setting up the grill or smoker for indirect heat to cook at 275°F.
This seems to be the sweet spot where its low enough that the outside doesn’t overcook but also high enough that the london broil doesn’t cook so long that it dries out.
Target Internal Temperature for London Broil
You HAVE to use a good instant read meat thermometer to know where the internal temperature is of your smoked london broil.
Remember there is not much fat on this cut of beef so if you over cook it even by a little bit it will dry out FAST!
If your london broil is thick enough, you want a good leave in probe thermometer like the Thermopro as well as a second instant read to spot check as you get close to pulling it off the smoker.
While we have used and recommended ThermoPro for years, lately we have also become big fans of the MEATER leave in thermometer.
It is extremely accurate and has an incredible 165 foot bluetooth range and works right with your smartphone so you don’t need to carry a separate controller around with you like many other remote thermometers require.
It’s got a great free app that is constantly being updated and even has an algorithm to predict how much longer your type of meat will take to cook based on cooking temperature, target temperature, current internal temperature.
It’s like a GPS for your meat!
Anyways, back to our smoked london broil…
We are going to slowly bring the internal temperature up to about 110°F, then crank the heat as hot as we can to reverse sear the london broil on each side for about 2-3 minutes. Then will continue cooking indirectly until it reaches 130°F and then remove it from the smoker.
Believe it or not, tougher steaks like london broil taste better when cooked to medium vs medium rare. This is because they can remain unpleasantly chewy if not cooked up to the proper temperature.
You will notice most flank steak cooked for tacos and fajitas, is cooked to at least medium or medium well so that it is not too chewy or unappetizing.
By marinating, letting the meat rest, and slicing against the grain, it will still be very tender and juicy!
Monitor your Temperature
You can’t do all this without accurate thermometers. There is very little room for error when smoking a london broil.
We are particular fans of this one from ThermoPro because of its durability and affordable price.
So keep it handy and use it often!
How Long Does it Take to Smoke a London Broil?
Most store bought London Broils will be in the 2-3 lb range and will take about 60 to 90 minutes to cook using this method.
If it is humid outside, or you crank the heat higher than 275°F, you can count on it cooking faster.
Use that instant read thermometer often.
Reverse Sear Method
“Reverse Searing” is just a fancy term for searing your meat at the very end, once it is pretty much all the way cooked through, in order to get a nice crispy exterior crust that you just can’t get from low and slow smoking alone.
This works great for thick cuts of meat like london broil that need time to slow cook and absorb smokey flavor but then benefit from a nice outside sear.
Much like our smoked ribeye steaks, we like to smoke and then reverse sear our london broil, simply by moving it over to the hot part of the grill or finishing it inside under the broiler.
If you are using a pellet grill and finding it hard to get that high direct heat for searing, try laying a couple of Grill Grates over a section of the grill. These work great for creating a hot searing stations on a pellet grill suing the ambient heat the pellet grill is already creating. See the pellet grill section below for more details.
Technically you can reverse sear in a hot pan with butter, a flat top grill with oil, or over a hot propane burner or searing hot batch of charcoal on any grill.
We just find with a large cut of beef like a smoked london broil it’s easier to keep it on the grill or if using a low temperature smoker, throw it under the broiler.
In order to reverse sear a london broil without overcooking it, only bring your internal temperature up to about 100-110°F on an internal meat thermometer. Then immediately sear it hot and fast for about 2-3 minutes on each side.
Then check your temperature again and place the meat back in the smoker or on the indirect side of the grill until the internal temperature hits 130°F.
No Reverse Sear
Sometimes, like with the smoked rack of lamb, we can go either way on whether to bother with a the reverse sear. Sometimes just smoking the meat up to the right temperature works well enough by itself.
Not so much with steaks.
You really need to reverse sear them.
It doesn’t matter which method you choose, but just smoking the steaks low and slow until they are finished is not an ideal way to cook them.
You won’t ever get that sizzling exterior crust or beautiful brown coloring form the maillard reaction that takes place at high heat.
Your thicker exterior fat will never render and the meat will remain an unappetizing gray color.
So take the extra 5 minutes, whether it’s over a hot grill burner, over some charcoal, or right nder the broiler in the oven, and sear that smoked london broil to finish it off.
You’ll be glad you did.
Setting up your Smoker for a Smoked London Broil
Vertical or Offset Charcoal Smoker
Fill your firebox or lower charcoal basin with about 1/4 a bag of unlit charcoal and create a small hollowed out depression in the center where you can add your lit briquets.
If your smoker comes with a water pan, like the Weber Smokey Mountain, fill the water pan as well to help stabilize the temperature and add moisture to the cooking chamber.
Light a charcoal chimney about 1/3 way with charcoal and wait about 20 minutes for it to fully ignite. You don’t want TOO many lit briquests initially or the temperature will get too high too fast and be unmanageable.
Fill your water pan first, then add the lit briquets to the center depression you created.
Keep the dampers about 1/2 way to 3/4 open until the temperature is to about 225 deg F. Then slowly close them down until you are maintaining a temperature of 275°F.
This will obviously take longer on a cold winter day than a hot summer one.
Add 1-2 chunks of smoking wood once the smoker is up to temperature and put your london broil on the cooking grate.
Plug your electric smoker in and turn the temperature to 275° F.
While it comes up to temperature, add smoking wood chips, not pellets, to the smoking wood tray.
Fill the water tray if there is one.
Close the door.
Fill the pellet hopper with your choice of smoking wood pellets.
Plug in the pellet grill and run it through its start up process.
Once it is creating smoke, turn the temperature to 275° F.
When the pellet grill has come up to temperature, place your london broil on the grill grates.
Never used a pellet grill before?
Read our ultimate guide to pellet grills to learn why they are so easy and how to set one up for success every time.
Getting a Sear on a Pellet Grill
Pellet Grills work great for smoking large cuts of meat like brisket, pork butt, and ribs, and maintaining a near perfect consistent air temperature, much like the best competition smokers promise to do.
The downside is their ability to sear at high heat like you would over direct coals or a propane gas burner.
In order to get the best of both worlds, we recommend coupling some Grill Grates with your pellet grill.
Grill Grates are specialty…well…grates that sit right over the existing grates on your pellet grill that help capture and direct all that ambient heat and give you a nice searing station in the corner of your pellet grill.
They claim to get temperatures up to 200°F HIGHER than the temperature you set your pellet grill, meaning even if your nice Trager only goes up to 400°F on the control panel, you can still sear some steaks, pork chops, or chicken at 600°F at the beginning or end of the cook to give them a nice sear.
Make sure to measure the size of your current grilling area.
While you absolutely CAN cover your entire pellet grill with Grill Grates, like if you were doing a batch of burgers for a big party, in our case we only want to cover PART of the pellet grill, maybe 1/3 to 1/2 of the cooking area for our pellet grill smoked London Broil.
Gas or Charcoal Grill
On a charcoal grill you can use wood chunks just like you would in a charcoal smoker.
On a gas grill you will likely need to use a smoker box filled with wood chips, or a pellet tube smoker filled with wood pellets.
Think you need a fancy smoker to smoke food at home? Think again. Great smoked food can be made right on your current gas or charcoal grill.
If you are unfamiliar with these gas grill smoking devices mentioned above, no worries, we have you covered!
In the case of a smoked ribeye roast, we would opt for the pellet tube smoker since it will provide you with a longer smoking time without needing to refill multiple times like a smoker box.
However either one will work just fine depending on what you have available.
Set up your gas or charcoal grill for indirect cooking with the burners or a small amount of lit briquets on one side and plan for your meat to be on the other side.
Once the temperature of your grill is about 275° F, place your wood chunks, smoker box, or pellet tube smoker over the coals or lit burners and once smoke begins coming out, place your meat on the opposite side.
How to Carve and Serve a Smoked London Broil
Resting the Meat
After reverse searing and then bringing the internal temperature up to 130°F, you will then remove the smoked london broil from the smoker, grill, or broiler and let it rest.
NO NEED to tent loosely with foil or any other nonsense or it will overcook from its own residual heat.
Put it on a large plate or cutting board and “Fugget About It” for 15 minutes! Get the veggies and sides ready or pour some drinks.
Let the smoked london broil rest for at least this long before carving.
Carving the Smoked London Broil
Use a good meat slicing knife and cut the smoked london broil in nice THIN strips, on a bias, against the grain.
Here’s a great tutorial if you need to educate yourself on this. Its a MUST with carving large steaks like London Broil.
You didn’t come this far just to cut it the wrong direction and leave your guests chewing each bite for minutes on end!
Using a good knife will also make life so much simpler. We particularly like this meat slicing knife from Mairico.
The outside slices may be more done than the very center if you have guests who prefer various levels of doneness.
What Other Foods Can I Smoke?
Looking for some more inspiration for things to smoke?
Check out some of our favorite recipes below that can easily be modified to be done on any grill or smoker.
More Smoked Beef
- Smoked Prime Rib on a Pellet Grill
- Smoked Ribeye Roast
- Hot and Fast Smoked Beef Brisket
- Smoked Corned Beef
- Smoked and Reverse Seared Ribeye Steaks
- Pellet Grilled Steak
- Perfect Grilled Hamburgers
More Smoked Pork, Turkey, and Chicken
- Smoked Fresh Ham with Dark Rum Citrus Glaze
- Pellet Grilled Pork Chops
- Spatchcocked Chicken on a Pellet Grill
- Smoked Turkey Breast with Cajun Butter Injection
- Spiral Sliced Smoked Hot Dogs
- Smoked Bratwurst with Beer Braised Onions
- Gas Grilled Bratwurst
- Pellet Grilled Bratwurst
- Pellet Grill Turkey
- Honey Smoked Salmon
- Smoked Oysters in a Garlic White Wine Sauce
- Smoked Scallops with Lemon Butter Sauce
- Smoked Lobster Tails
- Honey Smoked Tilapia
- Smoked Halibut with Garlic BBQ Rub
- Smoked Leg of Lamb with Guinness Marinade
- Smoked Lamb Chops with a Balsamic Butter Sauce
- Smoked Rack of Lamb with Garlic and Rosemary or Smoker
- Smoked and Pulled Lamb Shoulder with a Turkish Spice Rub
- Smoked Lamb Shanks
Other Odds and Ends
Trash Can Turkey – OK, technically not made on a pellet grill or smoker but one of the most fun ways there is to cook a Turkey…at over 700 degrees in only 2 hours!
You’ve got to check it out!
Smoked London Broil
- Large shallow glass baking dish
- Propane, Electric, or Charcoal Smoker -OR-
- a Pellet Grill, Charcoal grill, or Gas grill with a smoker box or pellet tube smoker.
- Hickory, Pecan, or Mesquite Wood chips, chunks, or pellets
- Instant Read Thermometer
- Broiler (Optional)
- Foil Lined Baking Sheet (optional)
- 1 2-3 lb London Broil
- ¼ Cup Vegetable Oil
- 3 Tbsp Red Wine Vinegar can also substitute apple cider vinegar
- 2 Tbsp Kosher salt
- 1 Tbsp Fresh black pepper
- 2 tsp Paprika
- 1 tsp Garlic Powder
- 1 tsp Onion Powder
Marinate the London Broil Overnight
- Remove the London Broil form the packaging and trim any excess fat from the edges. Place in a Large glass baking dish that can be covered.
- Mix the rub ingredients together in a small bowl.
- Whisk the oil and vinegar together in another bowl and then pour over the london broil making sure to coat both sides well.
- Generously season both sides of the london broil with the rub and place back in the glass baking dish, cover, and place in the refrigerator.
- Let the london broil marinate for at least 2 hours, preferably overnight.
Set up the Grill or Smoker
- Remove your london broil from the refrigerator but leave in the marinade until you are ready to place on the smoker.
- Set up your smoker, pellet grill, or grill with indirect heat to 275°F.
- When the smoker or grill is up to 250°F, add your wood chunks to the coals, or wood chips the tray or smoker box. Alternatively, you can add wood pellets to a pellet tube smoker. Place the smoker box or pellet tube smoker over the hot coals or burners.
- When smoke begins to come out the vents, place your london broil on the grate, away from the direct heat if using a grill.
Set up Broiler (Optional)
- If you are using a grill, you can reverse sear the london broil directly on the hot side of the grill. However, if you are using a pellet grill or smoker that does not provide direct heat, preheat your broiler an place the top oven rack at its highest position.
Smoking the London Broil
- Monitor your london broil internal temperature. After about 45-60 minutes your steak should reach an internal temperature of 100-110°F.
Reverse Searing the London Broil
- Once the london broil reaches 100-110°F internally, either move it over to the HIGH direct heat side of the grill, or, place it on a foil lined baking sheet and position it under the preheated broiler.
- Cook the steak with HIGH direct heat for about 2-3 minutes on each side
Rest, Slice, and Serve
- Remove the smoked london broil form the direct heat and move it back to the indirect side of the grill or back into the smoker at 275°F until the internal temperature reads 130°F on an instant read thermometer for a medium level of doneness. (The internal temperature will rise another 5°F while resting.)
- Remove the london broil from the grill or smoker and place on a large cutting board, uncovered to rest for 15 minutes before carving.
- Slice in thin strips, on a bias, against the grain of the meat with a good meat slicing knife. Serve immediately.