Heat 2 T. Oil in Heavy Medium Saucepan Over Medium Heat. Add Onions & Cook Until Golden, Stirring Occasionally, About 5 Min. Stir in Tomato Sauce, Garlic, Oregano & Italian Seasoning. Simmer Until Thickened, About Five Minutes. Heat Remaining 1 T. Oil in Skillet Over Medium Heat. Add Mushrooms & Zucchini & Cook Until Tender, Stirring Occasionally, Aboutfive Min. Set Aside. Preheat Oven To 350. Place Tortillas On Baking Sheet & Bake Until Crisp, About 4 Min. Spread About 1/4 C. Sauce Over Each. Sprinkle Each With 1/4 C. Cheese. Top Pizzas With Mushrooms, Zucchini, Peppers & Olives. Bake Until Cheese Melts, About 5 Min. Serve.