Old-Fashioned Black Bean Soup
- Combine the drained beans, ham bone or hock, and broth in the slow cooker. Cover and cook on High until boiling, about 1 hour.
- Meanwhile, in a large skillet over medium heat, melt the butter. Add the onions, garlic, and celery and cook, stirring a few times, until softened, about 5 minutes. Add to the cooker along with the marjoram and bay leaf. Cover, turn the cooker to Low, and cook the soup for 7 to 8 hours.
- Stir in the salt, pepper, and sherry, cover, and continue to cook on Low 15 minutes longer.
- Discard the bay leaf and ham bone, returning any bits of meat left on the bone to the soup. Puree in batches in a food processor or in the cooker with a handheld immersion blender. Taste to adjust the seasonings. Add some boiling water to thin, if desired. Ladle into soup bowls and serve hot.