Soak beans in cold water overnight, filling pot with water to about 3 inches
above beans. Drain beans; set aside.
Melt butter in a heavy stockpot. Add onion and carrots. Place a sheet of
aluminum foil or parchment paper over vegetables, then cover pot with lid. Cook
over medium heat until vegetables are soft, about 5 to 8 minutes. Do not brown.
Stir in chicken stock and chicken base. Add ham hock. Cook until ham hock is
tender, about 30 minutes. Add beans; cook until tender, about 60 minutes more.
Remove ham hock. When cool enough to handle, remove meat from bone, dice and add
Stir in diced ham and ground cumin. If soup is too thin, crush some beans in the
pot or remove some beans and puree, adding them back to the soup. If soup is too
thick, add more chicken stock. Season with salt and pepper to taste.