Oohs and ahhs follow the presentation of a perfectly cooked London broil at a celebration or family event. Though you may see beef labeled "London broil," the term actually is a method of cooking, not a cut of beef. Generally, the steak used to make London broil is flank steak that is marinated, broiled to perfection and sliced across the grain.
The cooking time for London broil varies depending on the cooking method. In general, London broil is cooked to medium rare, or 125 degrees Fahrenheit.
Make the Marinade
Marinades vary from old-school mixtures of garlic, onion, pepper, salt, olive oil, Worcestershire sauce and an acidic liquid such as lemon juice or vinegar to sweeter combinations that may feature brown sugar, honey, Italian seasoning, mustard, pineapple juice, soy sauce, beef stock and balsamic vinegar.
Place the flank steak in the marinade and put it in the refrigerator. Marinate it at least overnight and up to two days for a stronger flavor. After removing the steak, if you want to use the marinade as a dipping sauce, put it in a saucepan and bring it to a boil. Cook it at a low boil for 10 to 15 minutes and then keep it warm until ready to serve.
Broil a Perfectly Cooked London Broil
Set the oven or broiler to the broil setting. While the oven heats, remove the steak from the marinade. Remove any bits of onion or garlic because they will burn in the broiler. Pat it dry and brush it with your favorite oil and sprinkle with salt and pepper. Broil for 12 to 15 minutes on each side or until a meat thermometer inserted through the side records 125 degrees Fahrenheit, which is medium rare, the ideal temperature for a London broil.
Remove the steak from the broiler and place it on the cutting board. Tent aluminum foil over the meat to keep it warm. After allowing it to rest for 10 minutes, slice it into thin slices against the grain. Serve immediately.
Pan Fry the Steak
Heat a grill pan over medium-high heat. Place the steak on the hot pan and cook for three to four minutes. Lift the steak and rotate it 45 degrees. Allow it to cook for another three to four minutes. Turn the steak over and repeat the process to cook the meat quickly and produce the crosshatched grill marks on the finished London broil.
When the internal temperature reaches 125 degrees, remove it from the heat. The total cooking time is approximately 12 to 16 minutes. Let the meat rest on the cutting board covered with foil for 10 minutes. Slice thinly across the grain.
Out on the Grill
Heat one side of the grill to medium high. Place the marinated steak on the grill over the flames and sear for two to four minutes. Lift the steak and rotate it 45 degrees to produce the diamond-shaped grill marks. Sear for another two to four minutes. Turn the steak over and repeat on the other side.
Once the steak is nicely browned, move it to the other side of the grill and continue cooking with indirect heat for up to 30 minutes until the internal temperature is between 125 and 135 degrees. Remove it from the grill and allow the meat to rest for approximately 10 minutes before slicing against the grain.
Cook It to Well Done
While technically not a "London broil," you may prefer your steaks cooked to medium or well done. Alternative methods of cooking the steak include oven roasting and slow cooking in a Crock-Pot. Treat the flank steak like a roast.
You can choose to brown it quickly in a tablespoon or two of oil in a large frying pan or simply put it in a casserole dish, roasting pan or Crock-Pot. Add spices and at least 1/2 cup of beef broth, marinade or water. Cover and bake at 350 degrees for 20 to 25 minutes per pound. If you use a Crock-Pot, cook on low for up to eight hours or on high for four to five hours.