What is the best way to cook a shoulder London broil steak to ensure it is tender and flavorful?

The best way to cook a shoulder London broil steak to ensure it is tender and flavorful is to marinate it for several hours before cooking, then sear it on high heat for a short time to lock in the juices, and finish cooking it on a lower heat until it reaches your desired level of doneness. Resting the steak before slicing it will also help retain its juices and tenderness.