Rinse and soak the dried beans. Drain and add to a large saucepan.
Fill the saucepan with water (and add 2 cups of broth if you'd like additional flavor), so it covers the beans with at least 1 inch of liquid.
Add the mangoes, chopped cilantro, cumin and some salt and pepper. Bring to a boil, then reduce heat to medium, cover and cook for an hour. After an hour, test the softness of the beans. Cook longer, checking every 10 minutes, if the beans are not tender.
Prepare rice or other side dish.
Serve Black Beans with Mango & Cilantro over brown rice or with other side dish.