Cheese-Topped Zucchini
["3 medium zucchini", "1 medium onion, sliced thin", "1 Tbsp. salad oil", "1/2 tsp. crushed oregano", "1 (8 oz.) can tomato sauce", "1 (8 oz.) pkg. Mozzarella cheese", "grated Parmesan cheese"]
["Cut zucchini in half lengthwise.", "In a large skillet, cook onion in hot oil until tender, but not browned.", "Add zucchini halves, cut side up.", "Sprinkle with salt, pepper and oregano. Pour tomato sauce over.", "Cover.", "Cook just until tender, about 10 minutes.", "Top zucchini with Mozzarella cheese slices.", "Sprinkle with Parmesan cheese."]
["zucchini", "onion", "salad oil", "oregano", "tomato sauce", "Mozzarella cheese", "Parmesan cheese"]