Black Bean Soup provides a hearty one-pot meal by itself, but we also like to serve this soup with tortillas or cheese tortillas.
Rinse beans under running water and pick through, discarding any stones. Place beans in a large pan. Cover with 3 cups water and bring to a boil. Boil for 2 to 3 minutes, remove from heat, cover and let stand for 4 hours. Rinse beans and drain. Place beans in a large, clean pot, pour fresh cold water over until covered by 1 inch and bring to a boil. Reduce heat and simmer until beans are tender, about 1 1/2 hours. Let cool for 30 minutes.
Warm oil in large pan over medium heat. Cook onion, stirring, until it begins to soften, 2 to 3 minutes. Add chili powder and cumin, if desired. Sauté for 1 minute. Add tomatoes, beans, salt and 1 cup water; bring to a boil. Reduce heat to medium-low, cover and simmer for 10 minutes. Remove from heat; stir in 1 Tbsp. juice, if desired. Top with low-fat sour cream, salsa or chopped cilantro just before serving, if desired.