1In large resealablefood-storage plastic bag, place beef, bell pepper, squash, mushrooms and tomatoes. Mix 1/2 cup dressing and the ground pepper. Pour over beef and vegetables; seal bag and turn to coat. Refrigerate at least 1 hour but no longer than 4 hours, turning bag occasionally. Soak skewers in water about 1 hour to prevent burning.
2Heat coals or gas grill for direct heat. Remove beef and vegetables from marinade; discard marinade. Remove skewers from water. Thread 1 or 2 pieces beef on each skewer. Add a mushroom, squash, bell pepper piece or tomato to end of each skewer.
3Cover and grill kabobs 4 to 6 inches from medium heat 6 to 8 minutes for medium beef doneness, turning frequently.
4Arrange romaine on serving platter. Top with kabobs. Spoon additional dressing into small bowl for dipping; sprinkle with chives.