How to Cook Tender London Broil: Marinade, Grill, Broil & Slice

London broil stands out as an economical beef cut that, when handled correctly, delivers restaurant-quality tenderness and bold flavors. Typically sourced from the flank or top round, this lean muscle benefits from strategic preparation to break down its fibers and infuse taste. This guide explores everything from selecting the right cut to perfect execution, drawing on proven techniques for home cooks.

Understanding the London Broil Cut

London broil isn’t a specific primal cut but rather a method of preparation applied to tougher sections like flank steak or top sirloin. These areas come from the cow’s hindquarters, where muscles work hard, resulting in dense texture. The key to success lies in marinating to tenderize and slicing thinly against the grain post-cooking, which shortens muscle fibers for easier chewing.

• Flank Steak: Long, flat, and intensely beefy, ideal for high-heat cooking.
• Top Round: Slightly thicker, leaner option suited for roasting or broiling.
• Top Sirloin: Balances flavor and tenderness, often 1.5-2 inches thick for even cooking.

Opt for cuts at least 1.5 inches thick to avoid overcooking the interior while searing the exterior.

Essential Ingredients for Success

Great London broil starts with quality components. Focus on fresh acids, umami boosters, and sweeteners in your marinade to penetrate the meat.

Signature Marinade Recipes

Classic Balsamic Soy Marinade

This versatile blend yields juicy results in 2-6 hours. Combine 1/4 cup balsamic vinegar, 1/4 cup tamari or soy sauce, 2 tablespoons Worcestershire, 2 teaspoons brown sugar, 3 crushed garlic cloves, and 1 cup beef broth. Submerge a 2-pound steak, refrigerate, and flip occasionally.

Herb-Infused Citrus Marinade

For brighter notes, mix 1/2 cup olive oil, 1/3 cup soy sauce, 1/4 cup balsamic, 2 tablespoons lemon juice, 2 tablespoons brown sugar, 1.5 tablespoons Worcestershire, 1 tablespoon Dijon mustard, and spices like onion powder, garlic powder, paprika, oregano, parsley, basil, thyme, rosemary, pepper, and a pinch of red pepper flakes. Perfect for flank steak up to 2.5 pounds.

Simple Grill-Ready Marinade

Quick option: 3/4 cup soy sauce, 2 tablespoons brown sugar, 1 tablespoon each minced garlic, lemon juice, olive oil, balsamic vinaigrette, and Worcestershire. Rest for at least 20 minutes before cooking.

Preparation Steps

1. Select and Prep: Choose well-marbled meat. Pat dry, score lightly if needed to absorb marinade.
2. Marinate: 2 hours minimum, up to overnight for deeper flavor. Avoid over-marinating to prevent mushiness.
3. Season: Remove from marinade, pat dry, apply kosher salt (1-2 teaspoons per 2 pounds) and black pepper.
4. Rest: Let sit at room temperature 30-60 minutes for even cooking.

Cooking Methods Demystified

Reverse Sear Technique

Ideal for thick cuts. Season with salt and pepper. Bake at low heat (225-250°F) until internal temperature hits 115-120°F for medium-rare (about 45-60 minutes for 2 pounds). Sear in hot neutral oil 2-3 minutes per side. Rest 10-20 minutes.

High-Heat Broiling

Marinate, pat dry, broil 4-6 inches from heat. 4-5 minutes per side for medium-rare on a 1.5-2 pound steak. Total cook time around 10-15 minutes.

Grilling Mastery

Preheat grill to medium-high. Sear direct heat until 130-135°F internal (about 6-8 minutes per side), then indirect to finish. Reverse sear on direct for crust.

Time Chart for 1.5-2 inch thick steak (Medium-Rare, 130-135°F internal):

Finishing Touches: Butters and Rubs

Elevate with compound butters. Soften 8 tablespoons butter, mix in 1.5 teaspoons lemon zest, 1 minced garlic clove, 1.5 tablespoons chives, and 2 tablespoons minced herbs (parsley, thyme, etc.). Dollop on hot steak.

Dry rubs work too: Combine coffee, oregano, coriander, salt, pepper for a bold crust, as in java-inspired versions.

Slicing and Serving Essentials

Rest 10-20 minutes tented in foil. Identify grain direction, slice perpendicularly in 1/4-inch pieces. This transforms toughness into tenderness.

• Sides: Mashed potatoes, roasted carrots, grilled veggies, salad.
• Sauces: Chimichurri, horseradish cream.

Common Pitfalls and Fixes

• Overcooking: Use thermometer; pull at 125°F for carryover to 135°F.
• Tough Meat: Marinate longer, slice against grain.
• Lack of Flavor: Generous seasoning post-marinade.

Recipe Variations for Every Diet

• Whole30/Paleo: Use coconut aminos instead of soy, skip sugar or use date syrup.
• Keto/Low-Carb: Reduce sugar, add xanthan gum for marinade thickness.
• Slow Cooker: Marinate, cook low 6-8 hours for shredded beef in Mongolian style.

Storage and Reheating

Refrigerate leftovers up to 4 days in airtight container. Reheat gently in 250°F oven to avoid drying. Slice cold for sandwiches.

Frequently Asked Questions

What is the best cut for London broil?

Flank steak or top sirloin, 1.5-2 inches thick, offers optimal tenderness and flavor.

How long to marinate London broil?

2-6 hours ideal; overnight maximum to tenderize without over-softening.

Can I grill London broil?

Yes, use two-zone method: sear direct, finish indirect to 135°F.

How do I make London broil tender?

Marinate with acid, cook to medium-rare, rest, and slice against the grain.

What’s the internal temperature for medium-rare?

130-135°F after resting.