Achieving a medium-rare London Broil on the grill typically involves 8-12 minutes of direct high heat, followed by resting, depending on thickness and grill temperature.
Grilling a London Broil to that ideal medium-rare can transform a simple cut into a memorable meal. This versatile piece of beef, often a flank steak or top round, benefits immensely from the intense heat of the grill, developing a beautiful crust while staying tender and juicy inside. Getting the timing right is key to unlocking its full potential, ensuring a delicious experience every time.
Understanding London Broil: More Than Just a Cut
London Broil isn’t a specific cut of beef in the way a ribeye or tenderloin is. Historically, it refers to a method of preparation: marinating and then broiling or grilling a large, lean cut of beef, often served sliced. Today, when you see “London Broil” at the butcher, it’s most frequently a flank steak or a top round steak.
- Flank Steak: Known for its robust beefy flavor and distinct grain. It’s relatively thin, making it quick to cook.
- Top Round Steak: A thicker, leaner cut from the hindquarter. It benefits greatly from marinating to tenderize it.
Both cuts are excellent candidates for the grill, offering a satisfying chew and absorbing marinades beautifully. Their leanness means they cook quickly and can become tough if overcooked, making precise timing crucial for a medium-rare finish.
Essential Prep for Grilling Success
Proper preparation lays the groundwork for a tender, flavorful London Broil. This stage is just as important as the grilling itself.
The Magic of Marinating
Marinating is non-negotiable for London Broil, especially for top round. Marinades tenderize the meat and infuse it with flavor. An effective marinade typically contains three components:
- Acid: Vinegar, citrus juice, or wine helps break down muscle fibers.
- Oil: Olive oil or vegetable oil carries flavors and prevents the meat from drying out.
- Flavorings: Herbs, spices, garlic, onion, soy sauce, or Worcestershire sauce add depth.
Allow the London Broil to marinate for at least 2 hours, or up to 24 hours in the refrigerator. Longer marinating times are beneficial for tougher cuts like top round.
Pre-Grill Steps
Before it hits the heat, a couple of quick steps ensure the best possible results.
- Pat Dry: Remove the steak from the marinade and pat it thoroughly dry with paper towels. Excess moisture prevents a good sear, leading to steaming instead of browning.
- Bring to Room Temperature: Let the steak sit out at room temperature for 30-60 minutes before grilling. This allows for more even cooking, preventing the outside from overcooking while the inside remains cold.
How Long To Grill London Broil For Medium Rare: The Timing Sweet Spot
Achieving that perfect medium-rare doneness requires a combination of high heat, careful timing, and the indispensable tool of a meat thermometer. The goal is a steak with a warm red center, tender and juicy.
For medium-rare, the target internal temperature is 130-135°F (54-57°C). Remember that the meat’s temperature will rise by a few degrees during resting, a process known as carryover cooking.
Grill Setup and Initial Searing
Preheat your grill to high heat, aiming for temperatures around 450-500°F (232-260°C). A hot grill is essential for a good sear, creating that desirable crust.
- Place the London Broil directly over the hottest part of the grill.
- Sear for 2-3 minutes per side to develop a rich brown crust.
Timing by Thickness
The total grilling time for medium-rare London Broil depends primarily on its thickness. Thinner cuts cook faster, while thicker cuts require more time.
| Steak Thickness | Total Grill Time (Medium-Rare) | Internal Temperature |
|---|---|---|
| 1 inch (2.5 cm) | 8-10 minutes | 130-135°F (54-57°C) |
| 1.5 inches (3.8 cm) | 10-12 minutes | 130-135°F (54-57°C) |
| 2 inches (5 cm) | 12-15 minutes | 130-135°F (54-57°C) |
Use an instant-read meat thermometer inserted into the thickest part of the steak, away from any bone, to confirm doneness. This is the most reliable method to ensure accuracy and food safety. According to the USDA, beef should be cooked to a minimum internal temperature of 145°F (63°C) for medium-rare, followed by a 3-minute rest, to ensure safety. For those who prefer a slightly rarer texture while understanding the risks, 130-135°F is the common target for chefs, relying on high-quality sourcing and proper handling.
Grilling Techniques for a Perfect Sear
Beyond timing, employing specific grilling techniques enhances the texture and flavor of your London Broil.
High Heat and Direct Grilling
Maintain a consistently high grill temperature throughout the cooking process. This ensures the Maillard reaction, responsible for the delicious browned crust and complex flavors, occurs efficiently.
- Clean Grates: Start with clean, oiled grates to prevent sticking.
- Direct Heat: Cook the London Broil directly over the flame or heat source for the majority of the cooking time.
- Single Flip: For optimal searing, flip the steak only once. Allow it to cook undisturbed on one side until a deep brown crust forms, then flip and cook the second side.
Achieving Grill Marks
For those appealing crosshatch grill marks, after the initial sear on one side, rotate the steak 45 degrees before flipping it to the second side. Repeat this on the second side. While aesthetic, it also indicates good contact with the hot grates.
The Critical Role of Resting
Once your London Broil reaches the desired internal temperature, remove it from the grill immediately. The cooking process isn’t finished yet; the resting period is just as vital as the grilling itself.
As meat cooks, its muscle fibers contract, pushing juices towards the center. If you slice into the steak right away, those juices will escape onto your cutting board, leaving the meat dry. Resting allows the muscle fibers to relax and reabsorb the juices, resulting in a more tender and flavorful steak.
- Transfer the grilled London Broil to a cutting board.
- Tent it loosely with aluminum foil. This keeps the steak warm while allowing steam to escape, preventing it from becoming soggy.
- Rest for 5-10 minutes. For a thicker London Broil (1.5 inches or more), aim for the longer end of this range.
During this rest, the internal temperature will continue to rise by a few degrees (carryover cooking), so factor this into your initial grilling temperature target.
Slicing Against the Grain: A Must-Do
Even a perfectly cooked and rested London Broil can be tough if sliced incorrectly. Slicing against the grain is the final, crucial step to ensure maximum tenderness.
What “Against the Grain” Means
Meat fibers, or “grain,” run in a specific direction through the steak. You can usually see these long, parallel lines on the surface of the cooked meat. Slicing against the grain means cutting perpendicular to these fibers, shortening them. This makes the meat much easier to chew and gives it a tender texture.
- Identify the direction of the muscle fibers.
- Using a sharp knife, slice the London Broil thinly, at an angle, across the grain.
Slicing thinly also contributes to tenderness, making each bite enjoyable.
| Doneness Level | Internal Temperature (Fahrenheit) | Internal Temperature (Celsius) |
|---|---|---|
| Rare | 125-130°F | 52-54°C |
| Medium-Rare | 130-135°F | 54-57°C |
| Medium | 135-140°F | 57-60°C |
Troubleshooting Common Grilling Challenges
Even with the best intentions, grilling can present a few hurdles. Knowing how to address them helps ensure consistent results.
- Uneven Cooking: If your grill has hot spots, rotate the steak periodically or move it to a slightly cooler part of the grill to ensure uniform doneness. Starting with the steak at room temperature also helps.
- Tough Texture: This is almost always a sign of overcooking or incorrect slicing. Always use a thermometer, rest the meat properly, and slice thinly against the grain.
- Flare-Ups: Dripping fat can cause flames to erupt, charring your steak. Keep a spray bottle of water nearby to quickly douse small flare-ups. Trim excess fat from the steak before grilling, or move the steak to a cooler part of the grill temporarily.
Essential Tools for Grilling London Broil
Having the right tools at hand makes the grilling process smoother and more precise.
- Instant-Read Meat Thermometer: This is your best friend for grilling. It eliminates guesswork and ensures your steak is cooked to the exact doneness you desire, every single time.
- Long-Handled Tongs: Essential for safely flipping and moving the steak on a hot grill without piercing it and losing juices.
- Grill Brush: A clean grill prevents sticking and ensures those beautiful grill marks. Clean your grates before and after each use.
- Sharp Carving Knife: A long, sharp knife is vital for slicing the rested London Broil thinly and against the grain, making it tender and enjoyable.
References & Sources
- U.S. Department of Agriculture (USDA). “fsis.usda.gov” The USDA provides guidelines for safe internal cooking temperatures for various meats, including beef.
