Rinse the black beans thoroughly.

Cover the beans with water and soak for at least 4 hours, or preferably overnight.

Drain the soaked beans, discarding the soaking water.

Place the drained beans in a saucepan with 3 1/2 cups of water or stock and salt.

Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 1 1/2 hours, or until the beans are tender.

While the beans are simmering, heat oil in a separate pan.

Saute the onions and garlic in the oil until softened.

Add the carrot, celery, and green pepper to the pan.

Add a little water to the vegetables to help them steam until tender.

Stir in the coriander and cumin.

Once the beans are tender and the vegetables are sauteed, add the sauteed vegetables to the beans.

Let the soup continue to simmer over the lowest possible heat.

Add the oranges, orange juice, sherry, black pepper, red pepper, and lemon juice to the soup.

Stir the soup to combine the ingredients.

Cover and cook for an additional 10 minutes to allow the flavors to meld.

Taste the soup and adjust the seasoning as needed.

If desired, thin the soup by adding water or thicken it by pureeing some or all of the soup in a blender.

Serve the soup hot, topped with sour cream or yogurt.