1 Combine the lime juice, olive oil, cilantro, oregano, salt and pepper in a glass bowl and mix well. Trim the chicken breasts, then add to the marinade. Cover lightly and marinate, turning the chicken occasionally, for 2 hours at room temp (or overnight in the fridge).

2 Prepare Black Bean Sauce while chicken is marinating. Place beans in a large sauce-pan or soup pan, and add all remaining ingredients. Bring to a boil, then reduce the heat and simmer, uncovered, for about 1 1/2 hours. Add additional water if needed. Remove bay leaves, then transfer the bean mixture to a food processor. Process well, adding water if needed to make desired consistency. (I haven't needed to add any, and I like the sauce moderately thick).

3 Preheat oven to 350? F, and prepare grill (gas or hot coals). Place the red onion slices in the bottom of a shallow, oven-proof dish, then cover with chicken breasts and marinade. Cover the dish loosely with aluminum foil, then bake for 15-20 minutes (only until the chicken is opaque). Remove the chicken breasts to a platter and set aside. Continue to cook the onions in the marinade (covered) for 10 minutes. Save the marinade for grilling.

4 Place the chicken breasts on the grill over very hot coals or gas flame, and grill until they are thoroughly cooked but still moist (approximately 2 minutes on each side). Drizzle with remaining marinade while cooking. Remove to platter when grilled.

Serve the grilled chicken with the red onions, drizzle with the black bean sauce. Garnish with sour cream, guacamole, tomatoes or fresh cilantro - or serve with a leafy green side salad - as desired.