Portuguese Kale Soup

(from Twelve Months of Monastery Soups by Brother Victor-Antoine d'Avila-Latourrette)

1 cup white beans
10 cups water, more if needed
2 large onions, chopped
1 pound kale, chopped
2-3 potatoes, peeled and cubed
1 6-ounce can tomato paste
1 teaspoon vinegar
4 garlic cloves, minced
sausage pieces of your choice: chorizo, Linguica, etc.
salt and pepper to taste

Soak beans overnight. Rinse in cold water.
Briefly saute all ingredients in a bit of olive oil. Add water to the same pot and bring to a boil. After it comes to a boil, lower heat to medium and cook slowly for two hours. Add more water if necessary. Stir from time to time so the soup does not burn to the bottom of the pot.
When soup is done add the seasonings and stir the soup well. Turn off heat, cover the soup pot, and let it stand 10 minutes before serving. Serve hot.