How to Cook London Broil for a Tender, Juicy Result

London broil is a cooking method, not a specific cut of beef. The name is most often used for a lean, thick steak—commonly flank steak or top round—that is marinated, cooked quickly with high heat, rested, and sliced across the grain. Done well, it has a browned exterior and slices that are easier to chew. Plan ahead for marinating, and use a thermometer rather than judging doneness by color.

What You’ll Need

One 1½- to 2-pound flank steak or top-round steak, about 1 to 1½ inches thick
¼ cup olive oil
¼ cup soy sauce
2 tablespoons lemon juice or red wine vinegar
2 minced garlic cloves, or ½ teaspoon garlic powder
1 teaspoon black pepper; optional: 1 teaspoon dried herbs or 1 tablespoon Worcestershire sauce
A shallow dish or food-safe resealable bag, tongs, and an instant-read food thermometer
A broiler pan or rimmed baking sheet with a rack, or an outdoor grill
A cutting board and sharp knife

The marinade above seasons one steak; it is not a sauce for serving. If you want sauce, reserve some before it touches raw meat, or boil used marinade before serving it.

Step-by-Step

Mix the marinade. Combine the oil, soy sauce, lemon juice or vinegar, garlic, and pepper in a shallow dish or food-safe bag. Add herbs or Worcestershire sauce if you like. The acid adds flavor, while the oil helps coat the surface; marinating does not make a thick steak tender all the way through.
Marinate in the refrigerator. Put the steak in the dish or bag and turn it to coat. Cover the dish or seal the bag, then refrigerate for at least 2 hours and up to 12 hours. Turn it once if convenient. Do not leave raw beef on the counter to marinate, and do not extend an acidic marinade indefinitely; the exterior can become soft or mealy.
Prepare the cooking surface. For broiling, move an oven rack so the steak will sit about 4 to 6 inches from the heating element. Preheat the broiler according to the oven instructions, usually on high. For grilling, preheat the grill to high and clean and lightly oil the grates. Keep a close eye on the steak: broilers and grills can brown it quickly.
Take the chill off and dry the surface. Remove the steak from the marinade and discard the marinade unless you plan to boil it for safe use as a sauce. Pat the steak dry with paper towels so it browns rather than steams. Let it stand briefly while the cooking surface heats, but do not leave it out for an extended period.
Cook over high heat. For broiling, place the steak on a rack over a rimmed pan and broil, turning once, until browned and nearly at the doneness you want. For grilling, lay it over direct high heat and turn once. A 1- to 1½-inch steak may take roughly 5 to 8 minutes per side, but thickness, starting temperature, and equipment change the timing. Treat this as a guide, not a safety test; avoid letting sugary marinade residue burn.
Check the temperature correctly. Insert an instant-read thermometer sideways into the thickest part of the steak without touching bone or the pan. USDA guidance for whole cuts of beef is at least 145°F, followed by a 3-minute rest. Check more than one spot if the steak is uneven. Color and juices alone cannot reliably confirm a safe temperature.
Rest before cutting. Transfer the steak to a clean cutting board and let it rest for at least 3 minutes. This meets the USDA rest guidance for whole beef cuts and gives the juices time to settle. Do not put cooked meat back on the unwashed plate that held raw beef.
Find the grain and slice thinly. Look for the long muscle fibers running in one direction. Turn the steak so you can cut across those fibers, not parallel to them, making thin slices about ¼ inch thick. If the grain changes direction, adjust the angle as you go. Serve promptly.

Common Mistakes

Using time instead of temperature: A thick steak may need longer than expected, while a thinner one can overcook quickly. Use a thermometer and begin checking early.
Cutting with the grain: This leaves long, chewy fibers. Cutting across the grain shortens them and makes each bite easier to chew.
Skipping the rest: Cutting immediately can spill more juices onto the board. Rest the steak at least 3 minutes after it reaches 145°F.
Over-marinating: More time is not always better, especially with lemon juice or vinegar. Keep it refrigerated and limit the marinade to 12 hours for this recipe.
Cooking wet steak: Excess marinade can inhibit browning and drip or smoke under the broiler. Pat the surface dry before cooking.
Treating London broil as a cut: It is a preparation style. Check the package and thickness, because the steak may be flank, top round, or another lean cut.

Tips

Choose a steak of even thickness so it cooks more consistently. If one end is much thinner, fold it under or monitor that end closely.
Use a broiler-safe pan and follow your oven manual. Do not line a broiler pan in a way that blocks airflow or creates a fire risk.
For cleaner slices, use a sharp knife and cut across the grain at a slight angle. Thin slices are especially helpful with lean, firm cuts.
Let the steak’s thickness guide cooking, not a recipe’s exact minute count. Broilers vary, and a steak closer to the heating element browns faster.
If serving a sauce made from the marinade, bring it to a full boil before using it. An easier option is to reserve a clean portion before adding raw beef.

Troubleshooting

The outside is dark but the middle is underdone: Move the steak farther from the broiler element, or shift it to a cooler part of the grill. Continue cooking and check the center with the thermometer. If it is already very dark, lower the heat if possible rather than charring the surface further.
The steak is dry: It may have cooked too long, been cut too thickly, or been sliced with the grain. For this steak, verify the temperature promptly, rest it, and slice thinly across the grain. Serve with reserved sauce or pan juices; the next time, start checking earlier.
The meat is chewy: Confirm that you have cut across the visible muscle fibers. If you have and it remains firm, the cut may need thinner slices. A marinade can season the surface but cannot guarantee tenderness.
The marinade is burning or smoking: Remove the steak briefly, carefully wipe off excess marinade, and resume cooking while watching closely. Use a clean pan if drippings have begun to burn; never pour water onto a hot, greasy pan.
You do not have a thermometer: Doneness tests based on touch or color are unreliable. Use a food thermometer to verify the safe minimum rather than relying on timing; if needed, get one before preparing the steak.

Frequently Asked Questions

Is London broil a cut of meat?

No. It is a preparation method and menu name, often applied to flank steak or top round. The cut sold under that label can vary, so check the package.

Can I cook London broil on a grill?

Yes. Use direct high heat, turn the steak once, and check the thickest section with a thermometer. Grill temperature and steak thickness make cooking times vary.

How long should I marinate London broil?

For this recipe, marinate it in the refrigerator for at least 2 hours and no more than 12 hours. Keep raw beef cold throughout marinating.

Can London broil be served rare?

USDA guidance for whole cuts of beef is a minimum internal temperature of 145°F, followed by a 3-minute rest. Use a food thermometer to check; color alone is not a reliable safety measure.

How should I store leftovers?

Refrigerate cooked beef within 2 hours, in a covered container, and use it within 3 to 4 days. Reheat leftovers to 165°F, checking with a food thermometer. Freeze leftovers for longer storage if needed.

Can I make London broil without a marinade?

Yes. Season the steak with salt, pepper, and any preferred dry seasonings, then broil or grill it and slice across the grain. The result will be less tangy, but the same temperature and resting guidance applies.

Further reading: USDA FoodSafety.gov. Details can change, so check the official page for anything that matters to you. Spotted a mistake? Tell us. How we write an answer.