
1. In a slow cooker, combine the beans, onion, garlic, chipotle chile and sauce, cumin, bay leaves and oregano. Add 8 cups of water and 2 teaspoons salt and stir to combine. Cover and cook on low until the beans are tender, about 8 hours. Taste to ensure they’re all cooked through.
2. Remove the bay leaves. Transfer the onion, garlic and chipotle chile to a blender or food processor, along with about 2 cups of the beans and broth. (You can purée more or less of the soup, depending on desired consistency. I think it's best to purée sparingly.) Blend until smooth. Pour puréed soup back into the slow cooker, stir in the vinegar, then season generously with salt. Serve with desired toppings.
Leftovers will thicken overnight, so thin as needed with water or turn them into refried beans.