1Heat gas or charcoal grill. In medium bowl, toss mushrooms, bell pepper and 2 tablespoons of the dressing. Place vegetables in grill basket (grill “wok”).
2Place grill basket on grill over medium heat. Cover grill; cook 4 to 6 minutes, shaking grill basket to turn vegetables occasionally, until bell pepper is crisp-tender. Coarsely chop vegetables.
3Brush pizza crust with remaining 2 tablespoons dressing. Sprinkle with 1/2 cup of the cheese. Arrange tomatoes on cheese. Top with grilled vegetables, onions, olives and remaining 1/2 cup cheese.
4Place pizza directly on grill over medium heat. Cover grill; cook 8 to 10 minutes or until crust is crisp and cheese is melted.