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... 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. Continue Reading