1. Preheat oven to 350F. 2. Place Squash halves, cut side down, in baking dish. Add 1/4 cup water, and cover dish with foil. Bake for about 30 minutes, or until tender. Remove from oven, and cool slightly. 3. Meanwhile, heat 1 tablespoon oil in a large skillet over medium-high heat. Add Onion, and cook for 3 minutes, or until Onion is translucent. Add zucchini, reduce heat to medium, and cook for 4 to 5 minutes, or until zucchini begins to brown. Add tomatoes, salt and pepper. Reduce heat to low, and cook, uncovered, for about 10 minutes.