Generally speaking, a 6-ounce, 1.5-inch-thick steak takes 4 to 7 minutes to cook rare and 6 to 9 minutes to cook medium-rare. The thickness of a steak determines how long it will take to cook on a George Foreman Grill.
To cook a steak to medium-well or well-done, take the steak off of the grill exactly after 9 minutes have transpired. Place the steak on a plate and let it rest for 10 minutes. Then, cut the steak in the center to check the desired doneness. If the steak is not cooked to your liking, place the steak on the grill for an additional four minutes, then let it rest for 10 minutes and re-check it for desired doneness.