Polish Sour Soup (Żurek): Tangy Rye Soup Recipe

Polish sour soup, or żurek, is a tangy rye-fermented soup usually served with smoked sausage, potatoes, and a hard-boiled egg. This home-style version balances the starter’s sourness with savory broth and a little cream; recipes vary across Poland and from one household to another.

Ingredients

4 large eggs (about 200 g without shells), for serving
12 oz (340 g) fully cooked smoked kielbasa, cut into ¼-inch (6 mm) slices
1 medium yellow onion, about 5 oz (140 g), finely chopped
2 garlic cloves (about 6 g), finely chopped or grated
2 medium Yukon Gold or other waxy potatoes, about 12 oz (340 g), peeled if desired and cut into ½-inch (1.3 cm) cubes
6 cups (1.4 L) low-sodium chicken stock, or vegetable stock
1½ cups (360 ml) fermented rye żurek starter, stirred or shaken before measuring
1 tablespoon (15 ml) neutral oil or unsalted butter
1 teaspoon dried marjoram (about 1 g), rubbed between your fingers
2 bay leaves
3 whole allspice berries (about 1 g), or ¼ teaspoon ground allspice
½ teaspoon fine salt (about 3 g), plus more to taste
¼ teaspoon freshly ground black pepper (about 0.5 g), plus more to taste
½ cup (120 g) sour cream, brought close to room temperature
1 tablespoon (15 g) prepared horseradish, optional
2 tablespoons (8 g) chopped fresh dill, for serving

Instructions

Boil the eggs. Put the eggs in a saucepan and cover with cold water by about 1 inch (2.5 cm). Bring to a boil, cover, turn off the heat, and leave for 10 minutes. Transfer the eggs to cold water for 2 minutes, then peel and set aside. For whole boiled eggs, cook until the yolk and white are firm.
Prepare the soup ingredients. While the eggs cook and cool, chop the onion and garlic, cube the potatoes, and slice the kielbasa. Measure the stock, starter, and seasonings so they are ready to add. If the fermented starter has settled, stir or shake it well; the flour and liquid should be evenly mixed.
Build the broth. Heat the oil or butter in a heavy soup pot over medium heat. Add the onion and cook for about 5 minutes, stirring now and then, until softened but not deeply browned. Stir in the garlic for 30 seconds. Add the kielbasa, stock, bay leaves, allspice, salt, and pepper. Bring just to a boil, then lower the heat and simmer gently for 25 minutes.
Cook the potatoes. Stir the potato cubes into the broth. Keep the soup at a gentle simmer for 15 minutes, or until the potatoes are easily pierced with a fork but still hold their shape. Stir once or twice to prevent them from sticking to the bottom of the pot.
Add the rye starter. Pour in the stirred żurek starter gradually, tasting as you go if you prefer a milder soup. Add the marjoram and simmer gently for 5 minutes. Avoid a hard boil, which can make the soup taste harsher and may break down the potatoes. Remove and discard the bay leaves and whole allspice berries if you can find them.
Finish and serve. Whisk the sour cream in a small bowl with a ladleful of hot soup, then take the pot off the heat and stir the warmed cream mixture back in. Add the horseradish if using, then taste and adjust the salt, pepper, or marjoram. Let the soup stand for 5 minutes. Halve the eggs, ladle soup into bowls, and finish each serving with egg and dill.

Tips

Choose the right starter. Look for fermented rye żurek soup starter, often sold bottled or in a pouch in Polish or Eastern European grocery stores. It is not the same as a jar of ordinary bread yeast. If you cannot find it, use 1 cup (240 ml) rye sourdough discard mixed with 1 to 2 tablespoons (15 to 30 ml) lemon juice or cider vinegar, then adjust to taste. This shortcut gives acidity but not quite the same rounded fermented flavor.
Control the tang. Starter brands and batches vary in sourness. Begin with about 1 cup (240 ml), taste after simmering, and add more in small pours. If the finished soup is too sharp, stir in a little extra sour cream or stock rather than adding sugar.
Keep the texture gentle. A rolling boil after adding the starter or cream can make the soup less smooth. Simmer quietly, temper the sour cream with hot broth, and stir it in off the heat. For a thicker bowl, mash a few potato pieces against the side of the pot.
Season after the starter goes in. Kielbasa and stock can already be salty, while the starter changes how the seasoning tastes. Add salt in stages and do the final adjustment at the end. Fresh dill and horseradish are best added at serving, so their flavors stay distinct.

Serving Suggestions

Serve żurek hot as a filling first course or as a meal in its own right. Put half an egg in each bowl, or offer extra egg halves at the table for anyone who wants a heartier portion. Rye bread is a natural accompaniment: use it to mop up the sour, savory broth, or serve slices alongside with butter. A spoonful of horseradish gives each bowl a sharp finish, while chopped dill adds a fresh herbal note.

For a traditional-feeling spread, pair the soup with other simple Polish-style sides such as pickled cucumbers, sauerkraut, or a crisp green salad. The soup is rich and tangy, so a bright, crunchy accompaniment works better than another heavy dish. If serving several people, keep the pot warm over very low heat and arrange eggs, dill, and sour cream separately so everyone can garnish their own bowl.

Variations

Make it vegetarian: Use vegetable stock, skip the kielbasa, and add 8 oz (225 g) sliced cremini mushrooms. Brown the mushrooms with the onion before adding the stock; they add savory depth, though the result will not have the smoky, meaty character of the sausage version. Check that the rye starter is vegetarian if that matters to you.

Use fresh white sausage: Fresh Polish white sausage, or biała kiełbasa, is a common alternative to smoked kielbasa. Simmer it gently in the stock until cooked through, then check the center with a food thermometer: USDA FSIS recommends a safe minimum internal temperature of 160°F (71°C) for ground meat. Slice it before serving. Its flavor is milder and less smoky than kielbasa.

Adjust the potatoes and richness: For a more broth-forward soup, reduce the potatoes to 1 medium (about 6 oz / 170 g). For a creamier finish, use ¾ cup (180 g) sour cream, but temper it with hot broth before adding. You can leave out the horseradish for a softer flavor or serve it at the table for people to add as they like.

Make the starter shortcut work: If using rye sourdough discard rather than bottled żurek starter, whisk it smooth with some cool stock before pouring it into the pot. Add it gradually and taste before adding acid; some discard is already quite sour. The soup will be less traditionally fermented in flavor, but the rye and acidity still make a useful approximation.

Storage and Reheating

Refrigerate the soup within 2 hours of cooking in a covered container. It keeps for 3 to 4 days in the refrigerator. For the best texture, store boiled eggs separately and add them when serving; the potatoes can soften as they sit, and the broth may thicken. If the soup thickens, loosen it with a splash of stock or water when reheating.

Reheat only the amount you plan to eat in a saucepan over medium-low heat, stirring often until it is steaming throughout and reaches 165°F (74°C), the USDA FSIS safe temperature for leftovers. Avoid boiling it hard, especially after the sour cream has been added. Freeze soup for up to 2 to 3 months for best quality, preferably before adding sour cream; thaw overnight in the refrigerator, reheat to 165°F (74°C), and stir in fresh tempered sour cream. The texture of potatoes and cream may be a little less smooth after freezing.

Frequently Asked Questions

What is Polish sour soup?
Polish sour soup, usually called żurek, is a soup made sour with fermented rye starter. Common versions include stock, sausage, potatoes, marjoram, and hard-boiled egg, though ingredients and thickness vary by region and household. It is distinct from barszcz czerwony, the beet-based soup also known as red borscht.

Can I make żurek less sour?
Yes. Start with less starter than the recipe lists, simmer it briefly, and taste before adding more. A spoonful of sour cream or extra stock can soften an overly sharp bowl. Do not try to correct strong sourness by adding a large amount of sugar; that can make the soup taste oddly sweet without restoring balance.

Where can I buy żurek starter?
Check Polish or Eastern European grocery stores, especially near soups, pickles, or refrigerated fermented foods. It may be labeled żurek starter, fermented rye starter, or zakwas na żurek. Shake or stir it before measuring because rye flour often settles. A rye sourdough discard and lemon or vinegar can stand in, but the flavor will be less complex.

Can I make this soup without sausage?
Yes. Use vegetable stock and omit the kielbasa, or add browned mushrooms for more savory flavor. You can also use a plant-based sausage, but check its salt level before seasoning the soup. The rye starter, potato, marjoram, and egg still make a satisfying bowl, although it will differ from the smoked-sausage version.

Why did my sour cream curdle?
Sour cream is more likely to separate if it is cold when it meets very hot soup or if the pot boils after it is added. Let the cream lose its chill, whisk in a ladleful of hot broth to warm it gradually, then stir the mixture into the pot off the heat. The soup should stay hot, but it does not need to boil.

Can I prepare żurek ahead?
Yes. Make the soup a day ahead and refrigerate it promptly, then reheat it gently to 165°F (74°C) before serving. For the freshest texture, keep the boiled eggs, dill, and sour cream separate until serving. If making it well ahead for the freezer, freeze the soup before stirring in sour cream.

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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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