Preparation Cover beans with cold water by 3 inches in a bowl and soak at room temperature at least 8 hours, or quick-soak (see cooks' note, below). Drain well in a colander. Cook bacon in a 5- to 6-quart heavy pot over moderately high heat, stirring occasionally, until golden, about 5 minutes. Transfer bacon with a slotted spoon to a small bowl and pour off all but 1 tablespoon fat from pot. Reserve 2 tablespoons chopped bacon for topping, then return remaining bacon to pot and heat over moderately high heat until hot but not smoking. Add onion, bell pepper, garlic, chile, oregano, bay leaf, and thyme and sauté, stirring frequently, until onion is softened, about 5 minutes. Add beans, chicken broth, and white pepper and simmer, partially covered, stirring occasionally, until beans are very tender, about 2 1/2 hours. Discard bay leaf and stir in cilantro. Serve soup topped with sour cream, chopped cilantro, and reserved bacon. Cooks' notes:· To quick-soak beans, cover dried beans with 3 inches of cold water in a large saucepan. Bring to a boil and cook, uncovered, over moderate heat 2 minutes. Remove from heat and cover pan, then soak beans, covered, 1 hour. · Soup can be made 3 days ahead and cooled completely, then chilled, covered. Thin with water if desired when reheating.