Wash beans, discard imperfect ones. Place in a deep bowl and cover with water 2 inches above beans. Soak overnight.
Next day, drain beans and rinse well. In a large pot, add to the beans 2 tablespoons olive oil, bay leaf, 1/2 bruleed onion, 1/2 green pepper, tomato, and crushed garlic clove. Add enough water to fully cover beans plus two inches. Bring to a boil, then lower heat to moderate; cover and cook until beans are tender, about 1 hour.
Remove bay leaf and what is left of the tomato, onion, pepper and garlic. In a skillet, heat oil and saute the chopped onion and green pepper until caramelized. Add garlic, crushed oregano, cumin, sherry vinegar and salt. Stir to mix well and cook 2 minutes longer, then add to beans. Stir in hot sauce, cover and cook for 30 minutes. Correct seasoning, add additional sherry vinegar if necessary.
Serve with cooked long grain rice and lemon twist. Place cruets of olive oil, vinegar and hot sauce on table as condiments.