Put a pizza stone on the lowest rack of the oven. Preheat to 400'F.
(If you use a metal pan instead, do not preheat the pan.) Toss the vegetables with oil and vinegar. Cover 2 12" pizza shells with the cheese (leaving a 1/4" rim); sprinkle the vegetable mixture over the cheese. Slide the pizzas onto the pizza stone. Bake for 15 minutes, or until the crust is golden brown. Makes 2 Medium Pizzas, 8 Slices Each.