Combine steak, dressing, vinegar, and pepper in plastic food-storage bag. Secure with twist tie and marinate 10 minutes. Preheat broiler. Remove steak from marinade. Discard any excess marinade. Broil steak 6 inches from heat for 4 minutes each side for medium-rare or to desired doneness. Let stand 5 minutes. Slice thinly across the grain.