This soup is a good candidate for pressure cooking. Use unsoaked beans and only 5 cups water. Cook at full pressure for 30 minutes, and allow the pressure to release naturally for 15 minutes.
If desired, soak overnight in water to cover:
Heat in a soup pot over medium heat:
Add and cook, stirring, until softened, 6 to 8 minutes:
Add and cook for another minute:
Drain the beans, if soaked, and add to the pot along with:
Bring to a boil, then reduce the heat and simmer, partially covered, until the beans are completely tender, about 1 hour 15 minutes for soaked beans and 2 hours for unsoaked. Scoop 2 cups of beans into a small bowl or food processor and mash or process. Stir back into the soup and simmer for 5 minutes more to thicken. Taste the soup and season with more salt if needed. Serve in soup bowls with:
Excerpted from The Joy of Cooking, updated and revised by John Becker and Megan Scott. © Scribner, 2019.