Place beans in a Dutch oven; add water to cover by 2 in. Bring to a boil; boil for 2 minutes. Remove from the heat; cover and let stand for 1 hour. Drain beans; discard liquid.
Return beans to pan; add water to cover. Add onion and garlic; bring to a boil. Cover and cook over low heat for 2 hours or until beans are very tender, adding water to keep covered if needed. Discard onion and garlic. Mash beans with a potato masher, leaving some beans whole. Stir in cumin and hot pepper sauce.