MIX dressing, mustard, steak sauce and pepper in shallow dish. Add steak; turn to evenly coat both sides. Let stand 15 min. to marinate, turning occasionally.
REMOVE steak from marinade; discard marinade. Place steak on rack of broiler pan.
BROIL, 6 inches from heat source, 4 min. on each side or to medium doneness (160ºF). Let stand 5 min. before cutting across the grain into thin slices to serve.