1. Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).
2. Place sliced tomatoes and onion into a large roaster pan. Arrange chicken bottoms on top, skin side up.
3. Combine the remaining ingredients in a small bowl and spoon over the chicken bottoms.
4. Rub sauce into chicken, including under the skin. Stuff one to two tomato slices under the skin of each piece of chicken.
5. Cover pan tightly and bake for two hours. Uncover and raise oven heat to broil. Broil for an additional 15 minutes.