Soak the black beans overnight in water to cover.

Melt the butter in a stockpot.

Add the onions, leeks, celery stalk, bay leaves, and cloves to the stockpot and sauté for 3 minutes.

Add the ham shank and beef or veal bones and cook for 3-4 minutes.

Add the peppercorns and flour and blend well.

Cook for 2-3 minutes more.

Add 4-5 quarts of water and bring to a boil.

Reduce the heat, skim any impurities, and simmer covered for about 8 hours, leaving a small air space.

Strain the soaked beans and add them to the pot.

Simmer for 2 1/2 hours more, stirring occasionally.

Add more water if the mixture gets too thick or the beans are not completely covered.

Remove from the heat and discard the bones.

Put the soup through a food mill or coarse strainer to puree the beans.

Taste and adjust the seasoning.

Add the Madeira and bring to a boil.

Turn off the heat and serve immediately.

Garnish with chopped parsley, chopped hard-boiled eggs, and lemon slices.