How to Make It
Sort and wash beans; place in a large Dutch oven. Cover with water to 2 inches above beans; bring to a boil, and cook 2 minutes. Remove from heat; cover and let stand 1 hour. Drain beans in a colander; set aside.
Combine 1/2 cup water and chile in a small saucepan; bring to a boil. Remove water and chile from heat; cover and let stand 10 minutes or until chile is softened. Place water and chile in a food processor, and process 1 minute or until smooth. Set chile puree aside.
Heat oil in a Dutch oven over medium-high heat. Add onion and next 5 ingredients (onion through garlic); saute 7 minutes. Add beans, 2 tablespoons chile puree, broth, and next 10 ingredients (broth through bay leaf); bring to a boil. Cover, reduce heat, and simmer 1 hour. Discard bay leaf.
Remove 4 cups of beans and vegetables from soup with a slotted spoon; set aside. Place half of remaining soup in a blender; process until smooth, and pour into a bowl. Repeat procedure with other half of soup. Return pureed soup to pan, and stir in 4 cups of the bean-vegetable mixture. Cook soup over medium-low heat until thoroughly heated. Ladle soup into individual bowls; top with sour cream, and garnish with cilantro, if desired. Serve with remaining chile puree, if desired.