1. In a bowl soak the beans with water to cover, for at least 5 hours. Drain and wash. Put the beans in a large saucepan, cover with water and boil for 15 minutes. Add the garlic, onion and chili powder; lower the heat and simmer, uncovered for 1 hour or until soft.
2. Once they are cooked, add the salt. Check the seasoning and discard the garlic clove before serving.