Two types of pork -- bacon and spareribs -- and cabbage -- Savoy and sauerkraut -- are the stars in our version of the hearty Polish soup known as kapusniak.
In a large pot over medium-high heat, cook bacon and leeks, stirring occasionally, until most of fat is rendered and leeks have softened, 6 to 8 minutes. Transfer to a plate. Add spareribs and 5 quarts water to pot. Bring to a boil. Reduce heat to medium and boil, skimming foam and impurities from surface, until meat is tender and falls from bones easily, 50 to 55 minutes. Transfer ribs to a plate; let cool slightly. (For a clear soup, strain broth through a sieve lined with cheesecloth and return to pot before adding vegetables.) Add carrots, cabbage, potatoes, onion, sauerkraut, caraway seeds, and bacon mixture. Bring to a simmer, then reduce heat to medium-low and simmer, covered, until vegetables are tender and easily pierced with a knife, 22 to 25 minutes.
Meanwhile, slice ribs between bones and pull meat from bones. Cut off and discard any tough cartilage. Slice or tear meat into bite-size pieces. Stir meat into pot and simmer a few minutes to warm through. Season with salt and pepper to taste. Serve with dill, sour cream, bread, and butter.