By m2violin, member
Posted: January 3rd, 2013
Sift through your beans, discarding any little stones or clumps of dirt, and give them a quick rinse. Transfer to a large bowl, add enough cold water to cover the beans by 3 inches, and soak for 4 to 12 hours.
Drain and rinse the beans and transfer them to a 3- or 4-quart saucepan. Add the smashed garlic clove, bay leaf, and 6 cups cold water. Partially cover to limit evaporation and simmer gently, stirring every 20 to 30 minutes, until the beans are tender and almost creamy inside, without being mealy or mushy, approximately 1 to 1-1/2 hours. The beans' cooking time will vary depending on how old they are and how long they've soaked. So the safest way to determine when the beans are done is to taste them as they cook.
Season with 3/4 tsp. kosher salt when the beans are about three-quarters done. If at any time the liquid doesn't cover the beans, add 1 cup fresh water.
Drain the beans, reserving the cooking liquid, and discard the bay leaf (the garlic clove can stay).
Heat the olive oil or butter in a 4- to 5-qt. soup pot or Dutch oven over medium heat. Add kielbasa and cook, stirring often, until the fat is rendered and the kielbasa begins to brown, 5 to 8 minutes. Pour the kielbasa and fat into a small strainer set over a bowl, and set the kielbasa aside. Spoon 2 Tbs. of fat back into the pot and return it to medium heat.
Add the onions and celery and season with a pinch of kosher salt and freshly ground pepper. Cook, stirring frequently, until they begin to soften but not brown, 4 to 6 minutes.
Add the red pepper flakes, minced garlic, and tomato paste, and cook until fragrant, 1 minute more.
Add the potatoes, stirring to incorporate with the seasonings and aromatics, and then add 2 cups of broth, partially cover, and simmer until the vegetables are just barely tender, 10 to 20 minutes.
Add the beans, 1 cup of the reserved bean-cooking liquid, and 3 cups of broth. (If you have less than 1 cup bean liquid left from cooking the beans, adjust the broth for a total of 4 cups liquid.)
Return the cooked meat to the pot. Stir to combine and simmer, partially covered, for 10 minutes to meld the flavors.
Taste the soup and adjust the seasoning with vinegar, salt and pepper.
Ladle soup into bowls and serve.
Make-Ahead Note: You can cook the beans one day ahead; refrigerate the beans and the cooking liquid separately until you make the soup. The finished soup will keep in the fridge for three or four days, tightly covered. Or you can freeze it for up to three months.