The Best London Broil Marinade for Tender, Juicy Grilled Steak

London broil is not a cut of beef. It is a cooking method, and the steak behind it is usually lean top round or flank. Lean beef is flavorful but chewy, so the marinade does a lot of the work. The best London broil marinade balances salt, acid, fat, and sugar so the steak turns out savory, juicy, and easy to slice.

This guide gives you a tested-style recipe, exact marinating times, grill temps, and slicing steps. You will also get fixes for tough, gray, or salty steak.

Quick Answer: The best London broil marinade is soy sauce, olive oil, balsamic vinegar, Worcestershire, Dijon, garlic, brown sugar, and black pepper. Marinate 2 lb (0.9 kg) top round for 8-12 hours in the fridge. Grill at 450-500°F (230-260°C) to 125-130°F (52-54°C), rest 10 minutes, and slice thin against the grain.

Why This Best London Broil Marinade Works

Every ingredient has a job. Soy sauce brings salt and umami, which season the meat and help it hold moisture. Worcestershire adds depth, and Dijon helps the marinade cling to the surface.

Balsamic vinegar supplies acid. A little acid loosens the surface of the meat, but too much turns it mushy and gray. That is why this recipe uses a moderate amount and a set time limit.

Olive oil carries the garlic and spices, and it protects the steak from drying out over the high heat. Brown sugar adds a touch of sweetness and helps the crust brown. The sugar is also the reason you need to watch for flare-ups.

Marinades only penetrate a few millimeters. The real tenderness comes from three things: not overcooking, resting the meat, and slicing thin against the grain. The marinade adds flavor and a little surface tenderness. The technique does the rest.

Ingredients and Equipment

This makes enough marinade for one 2 lb (0.9 kg) steak and serves 4-6 people.

For the marinade:

• 1/2 cup (120 ml) low-sodium soy sauce
• 1/4 cup (60 ml) olive oil
• 1/4 cup (60 ml) balsamic vinegar
• 2 tbsp Worcestershire sauce
• 1 tbsp Dijon mustard
• 2 tbsp brown sugar
• 4 garlic cloves, minced
• 1 tbsp cracked black pepper
• 1 tsp dried thyme or rosemary
• 1/2 tsp smoked paprika (optional)

For the steak:

• 1 top round London broil, 2 lb (0.9 kg), 1.5 inches (3.8 cm) thick
• Kosher salt, a pinch, only if you use regular soy sauce sparingly
• 1 tbsp butter for finishing (optional)

Equipment: a gallon zip-top bag or shallow glass dish, a grill with a lid, long tongs, an instant-read thermometer, a cutting board, and a sharp carving knife. A good knife for cutting meat makes the slicing step much easier.

Substitutions

• Soy sauce: use tamari for gluten-free, or coconut aminos for a milder, sweeter flavor.
• Balsamic: swap in red wine vinegar or apple cider vinegar, 1/4 cup (60 ml).
• Brown sugar: use honey or maple syrup, 1.5 tbsp.
• Worcestershire: use extra soy sauce plus a splash of vinegar, though the flavor is less complex.

Choosing and Prepping the Meat

Top round is the classic London broil. It is lean, affordable, and sold in thick slabs of 1.5-2 inches (3.8-5 cm). Flank steak also works well and cooks faster. Sirloin tip is a good backup if your store labels it London broil.

Look for even thickness so the steak cooks uniformly. Pick a steak with a deep red color and little gray. If the package has a lot of liquid, pat the meat well when you get home.

Trim any heavy silver skin or thick hard fat. Leave a thin layer of fat, since it bastes the steak. Do not poke holes in the steak. Stabbing with a fork does not push marinade deeper in any meaningful way, and it lets juices escape.

Whisk the marinade in a bowl until the sugar dissolves. Place the steak in a zip-top bag, pour in the marinade, squeeze out the air, and seal. Lay the bag flat in a dish in case it leaks.

Marinating time:

Cut	Best Time	Maximum
Top round (1.5-2 in / 3.8-5 cm)	8-12 hours	24 hours
Flank steak (about 1 in / 2.5 cm)	4-8 hours	12 hours
Sirloin tip	6-10 hours	18 hours

Always marinate in the refrigerator, never on the counter. The USDA also says to keep raw meat and its juices away from food that will not be cooked. See the USDA FSIS guidance on grilling and food safety.

Pitmaster Tip: Flip the bag once or twice while it marinates, and take the steak out of the fridge 30 minutes before grilling. A steak that is not ice-cold sears better and cooks more evenly.

Step-by-Step: Grilling London Broil

1. Set up two zones. For gas, leave half the burners on high and the other half off. For charcoal, light a full chimney of lump charcoal and bank the coals on one side. New to lighting a fire? Read our guide on how to start a grill. Target 450-500°F (230-260°C) on the hot side.
2. Pull the steak from the bag. Let the extra marinade drip off, then pat the steak dry with paper towels. Wet meat steams instead of searing. Discard the used marinade, or save a portion that was never in contact with raw meat.
3. Clean and oil the grates. Scrub with a grill brush, then wipe the grates with an oil-soaked paper towel held in tongs.
4. Sear the first side. Place the steak on the hot side and close the lid. Sear for 3-4 minutes without moving it, until you see a deep brown crust and grill marks.
5. Flip and sear again. Turn the steak once and sear the second side for 3-4 minutes.
6. Move to indirect heat. Slide the steak to the cool side and close the lid. Cook 5-10 minutes more, depending on thickness.
7. Check the temperature. Insert the thermometer into the thickest part. Pull the steak at 125-130°F (52-54°C) for medium-rare. It will rise 5-8°F (3-4°C) while it rests.
8. Rest. Move the steak to a cutting board and let it sit for 10 minutes. Do not cover it tightly, because that steams the crust.
9. Slice thin. Carve against the grain at a slight angle into slices 1/4 inch (6 mm) thick.

Common Mistake: Cooking London broil past medium. Lean top round has very little fat, so it turns dry and chewy fast above 145°F (63°C). Use a thermometer, not guesswork or the clock.

If you want to simmer a glaze, boil a fresh batch of reserved marinade for several minutes. A side burner on a gas grill is perfect for this. Never brush raw-meat marinade on cooked steak without boiling it first].

Time and Temperature Table

The USDA says whole cuts of beef are safe at 145°F (63°C) with a 3-minute rest, per the safe minimum internal temperature chart . Many cooks prefer lower “pitmaster pull” temps for tenderness. Lean top round is best at medium-rare to medium.

Doneness	Pull Temp	Final Temp After Rest	Look and Feel
Rare	115-120°F (46-49°C)	125°F (52°C)	Cool red center, very soft
Medium-rare	125-130°F (52-54°C)	130-135°F (54-57°C)	Warm red-pink, springy
Medium	135-140°F (57-60°C)	140-145°F (60-63°C)	Pink center, firmer
Medium-well and up	150°F+ (66°C+)	155°F+ (68°C+)	Gray-brown, dry and chewy

Grilling times (steak 1.5 inches / 3.8 cm thick, 2 lb / 0.9 kg):

Step	Heat	Time
Sear side one	Direct, 450-500°F (230-260°C)	3-4 min
Sear side two	Direct	3-4 min
Finish	Indirect, lid closed	5-10 min
Rest	Cutting board	10 min
Total cook time	12-20 min

How to Tell When London Broil Is Done

The thermometer is the best tool. Insert it from the side, into the center of the thickest part. Avoid touching the grate or hitting a pocket of fat.

Touch is a helpful backup. Press the center with your finger. Medium-rare feels like the fleshy base of your thumb when you touch your thumb to your middle finger. Firm and bouncy means medium or beyond.

Look at the juices. When you pull a medium-rare steak, the surface looks glossy with small beads of red-pink juice. After 10 minutes of rest, the cut face should be rosy with only a small pool of juice on the board. A big puddle means you cut too early.

Resting, Slicing, and Serving

Resting lets the juices redistribute. Give the steak a full 10 minutes. The internal temp will climb about 5-8°F (3-4°C) from carryover cooking.

Slicing is where tough London broil is saved or lost. Find the direction of the muscle fibers, which look like long parallel lines. Cut across them, not along them. This shortens the fibers so each bite feels tender.

Hold your knife at a 30-45 degree angle and make thin slices, about 1/4 inch (6 mm). Use long, smooth strokes. For a very large piece, cut it in half along the grain first, then slice each half across the grain.

Spoon the resting juices over the slices, and top with flaky salt, chopped parsley, or a pat of butter.

What to Serve With London Broil

This steak loves classic comfort sides. Think of anything that soaks up beef juices or adds crunch and brightness.

• Potatoes: Roasted baby potatoes, garlic mashed potatoes, or smoked baked potatoes.
• Vegetables: Grilled asparagus, charred broccolini, or sauteed mushrooms and onions.
• Breads: Warm cornbread or crusty rolls to mop up the juices.
• Salads: A sharp arugula salad with lemon and Parmesan.
• Sauces: Chimichurri, horseradish cream, or a simple pan sauce made with beef broth and butter.

For more side ideas that suit hearty beef dinners, browse our list of what goes with meatloaf. Most of those sides work just as well here.

Storing, Freezing, and Reheating Leftovers

Storing: Cool leftovers quickly and refrigerate within two hours, or within one hour if it is above 90°F (32°C). The USDA says cooked leftovers are generally good for 3-4 days in the refrigerator . Store sliced steak in an airtight container with a spoonful of juices.

Freezing raw steak in marinade: You can freeze the raw steak in its marinade. Seal it flat in a freezer bag and freeze for up to 3 months for best quality. Thaw it in the refrigerator, not on the counter. This also works as a make-ahead step.

Freezing cooked slices: Wrap tightly, freeze, and use within 2-3 months.

Reheating: Reheat leftovers to 165°F (74°C), per the USDA]. To keep slices tender, warm them gently in a skillet with a splash of beef broth for 1-2 minutes. Cold sliced London broil is also great on sandwiches and salads.

Variations: Charcoal, Pellet Grill, Gas, and Oven

Charcoal Grill

Charcoal gives the best crust. Use lump charcoal for high heat and a clean burn, and read our post on lump charcoal if you want to know how it compares to briquettes. Add one small chunk of oak or hickory to the coals for a hint of smoke. Keep the lid vents open for a hot fire.

Gas Grill

Preheat on high for 10-15 minutes. Gas heats evenly and makes temperature control easy. Turn one burner off to make the indirect zone, then follow the same sear-and-finish method.

Pellet Grill

Pellet grills run lower than a charcoal fire, so use the reverse sear. Smoke the steak at 225°F (107°C) until it hits 110°F (43°C), about 30-45 minutes. Then sear it at the highest setting, or on a cast iron skillet, for 1-2 minutes per side. If you are shopping for one, see the best pellet grills for beginners.

Oven Broiler Backup

No grill? Set a rack 4-5 inches (10-13 cm) under the broiler, and heat it for 5 minutes. Broil the steak on a foil-lined pan for 5-6 minutes per side, then check the temperature. If you cook a lot of beef indoors, our guide to roast beef in the oven has more pointers.

Marinade Twists

• Asian-style: Use soy, ginger, sesame oil, garlic, and rice vinegar.
• Citrus and herb: Use orange juice, lime, cilantro, garlic, and olive oil. Keep this one to 4-6 hours, since citrus is strongly acidic.
• Spicy: Add 1-2 tsp chipotle powder and a squeeze of lime.

Troubleshooting London Broil

Problem	Likely Cause	Fix
Tough, chewy steak	Overcooked or sliced with the grain	Pull at 125-130°F (52-54°C) and slice thinly against the grain
Mushy, gray surface	Marinated too long or too much acid	Stay under 24 hours and keep acid to 1/4 cup per 2 lb
Too salty	Regular soy sauce or too long in marinade	Use low-sodium soy and skip extra salt
Weak crust	Steak was wet or grill was not hot enough	Pat dry and preheat to 450-500°F (230-260°C)
Burnt outside, raw inside	Too much direct heat	Move to indirect after searing
Flare-ups	Dripping oil and sugar	Wipe off extra marinade and move the steak off the flames
Bland flavor	Marinated under 4 hours	Marinate 8-12 hours and season the slices with flaky salt

Recipe Card: Best London Broil Marinade

Servings	4-6
Prep time	15 minutes
Marinate time	8-12 hours
Cook time	12-20 minutes
Rest time	10 minutes
Grill temp	450-500°F (230-260°C), direct then indirect
Pull temp	125-130°F (52-54°C) for medium-rare

Ingredients: 2 lb (0.9 kg) top round; 1/2 cup (120 ml) low-sodium soy sauce; 1/4 cup (60 ml) olive oil; 1/4 cup (60 ml) balsamic vinegar; 2 tbsp Worcestershire; 1 tbsp Dijon; 2 tbsp brown sugar; 4 garlic cloves; 1 tbsp black pepper; 1 tsp thyme.

Short steps:

1. Whisk the marinade and bag it with the steak. Refrigerate 8-12 hours.
2. Pat the steak dry and preheat the grill to 450-500°F (230-260°C).
3. Sear 3-4 minutes per side, then finish on indirect heat to 125-130°F (52-54°C).
4. Rest 10 minutes.
5. Slice 1/4 inch (6 mm) thick against the grain.

Frequently Asked Questions

What is the best marinade for London broil?

A balanced mix of soy sauce, olive oil, balsamic vinegar, Worcestershire, Dijon, garlic, and brown sugar works best. It adds salt, acid, fat, and sweetness without turning the lean beef mushy. Marinate 8-12 hours in the refrigerator for flavor that goes beyond the surface.

How long should you marinate London broil?

Marinate top round London broil 8-12 hours, with a 24-hour maximum. Flank steak needs only 4-8 hours. Too little time gives bland steak, while too long in an acidic marinade makes the surface mushy. Always keep it covered in the refrigerator.

What temperature should London broil be on the grill?

Grill over 450-500°F (230-260°C) heat, then pull the steak at 125-130°F (52-54°C) for medium-rare. It rises to about 130-135°F (54-57°C) while resting. The USDA minimum for whole beef cuts is 145°F (63°C) with a 3-minute rest.

How do you keep London broil from getting tough?

Do not overcook it, rest it 10 minutes, and slice it against the grain into thin slices. Lean top round dries out quickly above medium. A good marinade adds flavor and some surface tenderness, but technique makes the biggest difference.

Should you poke holes in London broil before marinating?

No. Piercing the steak does not drive marinade deep, and it lets juices leak out. Marinade works mainly on the surface. For better flavor, give the meat more time, use a bag so the liquid touches every side, and flip it occasionally.

Can you freeze London broil in the marinade?

Yes. Seal the raw steak and marinade in a freezer bag, press out the air, and freeze it flat for up to 3 months for best quality. Thaw it in the refrigerator for a day or two. Cook it within a day or two after thawing.

Conclusion

The best London broil marinade is simple: salty soy, bright balsamic, a little sugar, and plenty of garlic. Give it 8-12 hours, sear the steak hard, pull it at medium-rare, and slice it thin against the grain.

That is how a budget cut of beef turns into a juicy, flavorful dinner. Mix a batch of the best London broil marinade tonight, and you will have a great grilled steak ready tomorrow.