Black Bean Soup

Ingredients

• 1 pint (2 cups) dried black beans
• 2 quarts cold water (8 cups), plus more as it boils away
• 1 small onion, sliced
• 2 stalks celery, broken in pieces (or 1/4 teaspoon celery salt)
• 3 tablespoons butter, divided
• Salt, to taste (about 1 1/2 teaspoons)
• 1/8 teaspoon black pepper
• 1/4 teaspoon dry mustard
• Pinch of cayenne pepper
• 2 1/4 teaspoons cornstarch mixed with 2 tablespoons cold water
• 2 hard-cooked eggs, sliced thin
• 1 lemon, sliced thin, seeds removed

Method

1. Pick over the beans, cover with cold water, and soak overnight. Drain and add 2 quarts fresh cold water.
2. Cook the onion 5 minutes in half the butter; add it to the beans with the celery. Simmer 3 to 4 hours, until the beans are very soft, adding water as it boils away.
3. Rub the soup through a sieve (or blend until smooth) and return it to the pot. Bring back to a boil.
4. Stir in the salt, pepper, mustard, and cayenne, mixed together. Stir in the cornstarch slurry and simmer 2 minutes, until lightly bound.
5. Put the sliced eggs and lemon in a warm tureen or bowls, strain the soup over them, and serve.