An easy and low calorie side dish that could be served with any meat dish. I found this in Everyday Food magazine and have use Vidalia onions and added garlic for our taste. The Vidalia's are soooo sweet!
Preheat oven to 450 degrees. In a 9-by-13-inch baking dish, arrange tomatoes and onions in rows, overlapping slightly. Sprinkle with the minced garlic and drizzle with oil and season with salt and pepper. Bake until tomatoes are lightly browned and onions are tender, about 45 minutes. Serve warm or at room temperature.