On a cookie sheet, sort the black beans, removing any rocks, and wash the beans. Place the beans in a saucepan and cover with water. Bring to a boil and cook for about 1 hour. Drain beans and rinse. Return to the saucepan and cover with fresh water and cook another 4 to 5 hours, until tender, adding more water as necessary.
Once beans are tender, stir in mire poix of onion, carrot, celery, and garlic. Cook until vegetables are tender. Season with salt, pepper and cumin, to taste. Stir in the sherry.