London broil is a style of meat preparation, generally used for tougher cuts such as flank steak. Depending on the desired degree of cooking, a 1-inch flank steak can be grilled for 3 to 4 minutes per side and then cooked at a lower temperature for 2 minutes.
Lean cuts of meat such as flank steak are improved with marination and shorter cooking times. Soaking meat with an acidic liquid such as vinegar, lemon juice or wine breaks down tougher tissues, and spices added to the liquid enhance the flavor of the meat.
After marinating, flank steaks are preferably grilled to rare or medium completion. The cooking degree can be determined by lightly pressing the meat and testing for firmness. To serve in London broil style, slice the meat thinly across the grain, and add mashed potatoes on the side.