Soak beans overnight. Drain; rinse.
Sauté onion, chili powder, cumin, carrot and celery in oil in 7-quart Dutch oven or stockpot over medium heat until soft. Add salt and pepper. Soak pasilla chili in warm water until soft, then stem and seed. Add to chili with stock and ham bone or ham hock.
Bring to boil and simmer 11/2 to 2 hours, or until beans are cooked through.
Remove ham bone and adjust seasonings. Pureé half of soup in blender or food processor if desired.
Serve hot. Garnish with spoonful of sour cream and taco wedges or fried tortillas and minced chives.
Variation: also can be cooked in ovenproof casserole in 325 degrees F oven. Bring to boil on stove top before putting in oven.Makes 12 Source: