Soak black beans overnight or bring 6 cups of water to a boil with 1 teaspoon of salt.

Cover and simmer the beans for 3 1/2 to 4 hours, or until tender.

Crush together garlic, salt, cumin, oregano, and dry mustard to create a seasoning paste.

Heat olive oil in a large skillet.

Saute chopped onions in the oil for about 5 minutes, until softened.

Add chopped green pepper to the skillet and continue to cook until the onions are tender.

Stir in the seasoning paste, lemon juice, and 1/2 cup of bean liquid into the skillet.

Cover and simmer the skillet mixture for 10 minutes to meld the flavors.

Add the skillet mixture to the cooked black beans.

Cook the soup until the flavors blend together, about 1 hour.

Serve the Cuban black bean soup over rice.