I cook black beans plain in the slow cooker and then portion and freeze so I can pull them out for whatever recipe I need. I use the method I found online at budgetbyes. Rinse and sort a pound of black beans. Then put them in the slow cooker with 6 cups of water on high for 4-6 hours. Although I've cooked them on low for 8-10 hours as well. I drain and them before using or freezing.