HEAT barbecue to medium-high heat. Grill steak 5 min. on each side or until done (160°F). Transfer to cutting board; let stand 5 min.
MEANWHILE, toss lettuce with onions and croutons. Add dressing; mix lightly. Place on 4 serving plates.
CUT steak into thin slices; place over salads. Sprinkle with cheese.
