A London broil is not a cut of meat, but a manner of preparing the meat. London broils are famous for being especially moist and tender, and are most commonly made using top round roast. All London broils must be marinated, cooked until medium rare, and then cut across the grain into small strips to preserve the tender texture of the steak.
Allow the cooked London broil to sit for five minutes to give the juices an opportunity to distribute themselves across the steak. This will help prevent portions of the steak from becoming dryer than the rest.
Identify the grain of the London broil. It is similar to wood grain and resembles small lines running throughout the steak.
Start cutting the London broil into 1/8-inch strips against the grain at a 45-degree angle. This is a slight angle, which will create diagonal cuts in the steak.
Continue cutting until only steak strips remain. Serve the London broil with a prepared sauce to help keep the meat moist and juicy.
The longer you allow the steak to marinate, the tenderer and more flavorful it will be. It is common practice to allow steaks to marinate for up to 24 hours to reach optimum flavor.