1Heat beans and water to boiling in 8-quart Dutch oven. Boil uncovered 2 minutes; remove from heat. Cover and let stand 1 hour.
2Stir in remaining ingredients except cilantro and sour cream. Heat to boiling; educe heat to low. Cover and simmer 1 hour, stirring occasionally and adding water if necessary, until beans are tender.
3Stir in cilantro. Top each serving with sour cream; sprinkle with additional chopped fresh cilantro if desired.