Remove steak from marinade; discard marinade. Place steak in center of grid over medium, ash-covered coals. Grill steak, covered, 16 to 21 minutes (over medium heat on preheated gas grill, 11 to 16 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally.
Meanwhile, arrange peaches, tomatoes and lettuce on grid around steak. Grill peaches 2 to 4 minutes, tomatoes 2 to 3 minutes and lettuce hearts 1 to 2 minutes turning once.