Sort and wash beans; place beans in a large Dutch oven. Cover with water to a depth of 2 inches above beans. Bring to a boil; cover, remove from heat, and let stand for 1 hour. Drain beans, and set aside.
Place oil in Dutch oven; place over medium-high heat until hot. Add onion and next 7 ingredients; saute until onion is tender. Add broth and beans. Bring to a boil; cover, reduce heat, and simmer 1 1/2 hours or until beans are tender. Stir in chopped parsley. To serve, ladle soup into individual bowls. Garnish with nonfat sour cream and parsley sprigs, if desired.