Combine first 4 ingredients in a large bowl. Drizzle with oil, and sprinkle with salt and pepper, tossing to coat.
Grill vegetable mixture in a metal basket or grill wok coated with cooking spray, covered with grill lid, over medium-high heat (350° to 400°) 15 minutes or until vegetables are crisp-tender, stirring occasionally. Remove vegetables from basket; add tomatoes to basket, and grill, covered with grill lid, 1 to 2 minutes or until tomato skins begin to burst.
Note: If you don't have a grill wok or basket, place a 24-inch piece of heavy-duty aluminum foil on grill cooking grate. Make several 1-inch slits evenly in foil. Arrange vegetables on foil. Proceed as directed.