POUR 1/2 cup dressing over steak in shallow dish; turn to evenly coat both sides of steak. Refrigerate 30 min. to marinate.
HEAT grill to medium heat. Remove steak from marinade; discard marinade. Grill steak 5 to 10 min. on each side or until medium doneness (160°F). Remove from grill; cut steak across the grain into thin slices.
TOSS greens with tomatoes, squash and remaining dressing. Place on platter; top with meat and cheese.