Polish Sauerkraut Soup (Kapusniak) with Potatoes

Polish sauerkraut soup, often called kapuśniak, is a tangy, hearty soup made with sauerkraut, potatoes, vegetables, and smoked pork. Regional and family versions vary: this stovetop recipe uses kielbasa for a savory, smoky broth and is served hot with bread.

Ingredients

1 tablespoon (15 ml) neutral oil
12 ounces (340 g) smoked kielbasa, cut into ¼-inch (6 mm) slices
1 medium yellow onion, about 1 cup (150 g), diced
2 medium carrots, about 1 cup (120 g), peeled and diced
2 cloves garlic, minced
1 teaspoon (2 g) dried marjoram
½ teaspoon (1 g) caraway seeds, lightly crushed, optional
6 cups (1.4 L) low-sodium chicken broth
1 pound (450 g) Yukon Gold potatoes, peeled if desired and cut into ¾-inch (2 cm) cubes
1 pound (450 g) refrigerated sauerkraut, with ½ cup (120 ml) of its brine reserved
1 bay leaf
½ teaspoon (3 g) kosher salt, plus more to taste
¼ teaspoon (0.5 g) freshly ground black pepper, plus more to taste
2 tablespoons (8 g) chopped fresh dill or parsley, for serving
½ cup (120 g) sour cream, for serving, optional

Instructions

Prepare the sauerkraut. Taste it first. If it is very salty or sharply sour, rinse it briefly under cool water and drain; otherwise, use it as is. Roughly chop long strands so they are easier to eat. Reserve the brine separately.
Brown the kielbasa. Heat the oil in a large heavy pot or Dutch oven over medium heat. Add the kielbasa and cook for 5–7 minutes, stirring now and then, until browned in spots. Transfer it to a plate, leaving the rendered fat in the pot. Kielbasa is typically sold fully cooked; if using raw sausage instead, cook it through to 160°F (71°C) for pork or beef sausage, or 165°F (74°C) for poultry sausage, checking with a food thermometer according to USDA FSIS guidance.
Soften the vegetables. Add the onion and carrots to the pot. Cook for 5 minutes, stirring occasionally, until the onion starts to soften. Stir in the garlic, marjoram, and caraway, if using, and cook for 30 seconds, just until fragrant.
Simmer the potatoes. Pour in the broth and scrape up any browned bits from the bottom. Add the potatoes, bay leaf, salt, and pepper. Bring to a boil, then lower the heat to maintain a gentle simmer. Cover partially and cook for 15 minutes, or until the potatoes are almost tender when pierced with a knife.
Add the sauerkraut. Stir in the sauerkraut and browned kielbasa. Simmer uncovered for 20–25 minutes, until the potatoes are fully tender and the flavors have come together. Avoid a hard boil, which can break up the potatoes and make the soup cloudy.
Adjust and serve. Remove the bay leaf. Taste the broth before adding more salt; stir in reserved sauerkraut brine a tablespoon at a time if you want a brighter, tangier soup. Ladle into bowls and finish with dill or parsley. Offer sour cream at the table, if desired.

Tips

Season at the end. Sauerkraut, its brine, broth, and sausage all contribute salt. Start with the modest amount listed and adjust only after simmering.
Keep the potatoes intact. Cut them into similarly sized cubes, simmer gently, and wait to add the sauerkraut until they are nearly tender. Acid can slow how quickly potatoes soften.
Choose your sauerkraut carefully. Refrigerated, naturally fermented sauerkraut gives a fresh, clean tang. Shelf-stable canned sauerkraut works too, but may be softer or more mellow; drain it and add brine only to taste.
Make it meatless if needed. Omit kielbasa and use vegetable broth. For a smoky note, add ½ teaspoon (2.5 ml) smoked paprika with the garlic; it changes the soup’s flavor but keeps the savory character.

Serving Suggestions

Serve the soup hot in deep bowls with rye bread, crusty sourdough, or boiled potatoes on the side. A spoonful of sour cream softens the tang, while fresh dill or parsley adds a fresh finish. For a fuller meal, pair it with a simple cucumber salad or a slice of dark bread spread with butter.

Variations

For a more traditional pork-forward version, replace the kielbasa with 12 ounces (340 g) smoked pork shoulder or cooked ham, added with the sauerkraut. If using raw pork shoulder, simmer it in the broth until tender before adding the potatoes; whole cuts of pork should reach at least 145°F (63°C) and rest for 3 minutes, though shoulder is usually cooked longer until tender. For a lighter soup, use chicken sausage and chicken broth. Some versions include mushrooms or a little tomato; add 8 ounces (225 g) sliced mushrooms with the onion, or stir in 1 tablespoon (16 g) tomato paste with the garlic. Both additions shift the flavor, so add brine gradually at the end.

Storage and Reheating

Refrigerate leftovers within 2 hours of cooking in a covered, shallow container. The soup keeps for 3–4 days in the refrigerator. Reheat only the portion you plan to eat on the stovetop over medium heat or in the microwave, stirring as needed, until it reaches 165°F (74°C); USDA FSIS recommends that temperature for leftovers, checked with a food thermometer. Add a splash of broth or water if it has thickened. The soup can be frozen for up to 2–3 months for best quality; thaw overnight in the refrigerator and reheat to 165°F (74°C). Potatoes may soften slightly after freezing.

Frequently Asked Questions

What does kapuśniak mean?
Kapuśniak is a Polish name for sauerkraut soup. Recipes vary by region and household, but sauerkraut is the defining ingredient; versions may use smoked meat, fresh pork, or no meat at all.

Should I rinse sauerkraut before adding it?
Not always. Taste it first: rinse and drain it if it is too salty or intensely sour, but leave it unrinsed if you want a stronger tang. Reserved brine lets you add acidity gradually later.

Can I make Polish sauerkraut soup without kielbasa?
Yes. Use vegetable broth and leave out the sausage for a meatless soup. Smoked paprika adds a little smoky flavor, while sautéed mushrooms give the broth more savory depth.

Why are my potatoes still firm?
Sauerkraut is acidic, and adding it too early can slow the potatoes’ softening. Simmer the potatoes in broth until nearly tender before adding the sauerkraut, and keep the soup at a gentle simmer.

Can I make the soup ahead?
Yes. Cool and refrigerate it within 2 hours, then reheat it to 165°F (74°C) before serving. The flavors may meld overnight; loosen the soup with a little broth if it thickens.

Is this soup supposed to be very sour?
It should taste pleasantly tangy, but the intensity depends on the sauerkraut. Rinse some or all of it for a milder result, and add the reserved brine by the tablespoon only if you want more sharpness.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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