1. Combine the achiote paste, garlic, cumin, cinnamon, orange and lime juices, vinegar, salt and pepper in a blender. Puree until smooth. Pour into a nonreactive baking pan, add the chicken and turn to coat. Cover and marinate in the refrigerator 2 to 24 hours.
2. Preheat the oven to 375°F.
3. Cut six 16 x 14-inch sheets of heavy-duty aluminum foil. If using banana leaves, place 1 on top of each piece of foil. Center a piece of chicken on each, reserving the marinade. Top each with 2 tomato slices and 1 slice of onion. Wrap and seal the banana leaf and the foil to enclose. Place on a baking sheet. Transfer to the oven and bake 45 minutes.
4. Meanwhile, melt the butter in a medium saucepan over medium-high heat. Sauté the onions until golden brown. Stir in the reserved marinade, bring to a boil and cook, stirring frequently, 5 minutes. Add the chicken stock and cook 10 minutes longer. Reserve.
5. When the chicken is ready, remove from the oven and open the packets. Transfer the chicken, with the banana leaves if using, to serving plates. Pour any excess juices from the pan into the sauce. Pour the hot sauce over the chicken and serve with rice.Serving Size: 1 chicken breast with sauce