You do not need to soak black beans before cooking them. You can but it's not a necessary step. It is said that soaking beans helps aide with digestion. It will also help to soften the beans and help the cooking process along. This recipe was tested without soaking the beans. If you wish to soak your beans I would recommend doing so the night before you plan to make them and allow them to soak overnight. Simply place the beans in a large bowl with water covering them completely. Make sure to drain the water out before adding them to your Slow Cooker.