Name: Kujawy Sour Rye Soup (Żur kujawski)
Prep time: 25 min
Cook time: 50 min
Total time: 75 min
Yield: 6 bowls, about 400–450 ml each
Cuisine: Polish
Ingredients: 500 ml refrigerated fermented rye żur zakwas, stirred or shaken thoroughly before measuring; 1.5 l water; 500 g potatoes, peeled weight, cut into 2 cm cubes; 120 g smoked bacon, cut into small lardons; 200 g fully cooked smoked pork sausage, sliced; 100 g yellow onion, finely diced; 6 g garlic, about 2 cloves, finely chopped; 2 bay leaves; 4 whole allspice berries; 1.5 g freshly ground black pepper; 4 g dried marjoram, rubbed between your fingers; 120 ml pasteurized sour cream, 18% fat; Fine salt, only after tasting; add a little if needed; Fresh marjoram, optional for serving

A wide view of „Kujawy Sour Rye Soup (Żur kujawski)“ arranged on a table for serving.

Yield 6 bowls, about 400–450 ml each

Servings 6

Serving size one 400–450 ml bowl with potatoes and smoked pork

Prep time 25 minutes

Ingredients ↓

Recipe at a glance

Kujawy Sour Rye Soup (Żur kujawski)

A thick, gently sour Polish rye soup with potatoes, smoked pork, marjoram and a spoonful of sour cream.

Żur kujawski is a regional sour rye soup from Kujawy, in Poland’s Kujawsko-Pomorskie region. Its defining ingredient is zakwas: fermented rye flour and water, usually made from wholemeal rye. The finished soup is opaque and grey-beige, with a substantial texture and the clean, tangy character of the fermented rye.

The recorded tradition is deliberately flexible. Households could cook the soup with or without sausage, enrich it with cream or pork fat, and serve potatoes in the soup or separately, with bread or dumplings also documented. Everyday and holiday versions differed according to the season, fasting customs and what a household had available. The regional record confirms the dish’s identity, not one fixed formula.

This practical home version makes six bowls with refrigerated, prepared rye zakwas, potatoes cooked in the soup, smoked bacon, fully cooked smoked sausage, onion, garlic and marjoram. It follows the documented sour rye base and seasoning while making its measured ingredients explicit. Stir the settled zakwas before adding it, simmer gently until the soup thickens, then temper the sour cream so it blends smoothly.

Tips for success

Buy refrigerated fermented rye zakwas labeled for żur or żurek. Flour settles in the bottle, so shake it well or stir it thoroughly before measuring.
Keep the soup at a gentle simmer after adding the zakwas. Stir across the bottom of the pot so the rye solids do not catch as the soup thickens.
Cut the potatoes into even 2 cm cubes so they soften at roughly the same time. They are ready when a knife slides in easily.
Use fully cooked smoked sausage and heat it through in the soup. The recipe does not give a cooking time for raw sausage.
Add salt only after tasting the finished soup. Zakwas, bacon and sausage can all contribute different amounts of sodium.
Temper the sour cream with a ladleful of hot soup and stir it in off the boil to reduce the chance of a grainy texture.
The soup should be opaque, thick enough to coat a spoon lightly and clearly sour from the rye ferment; it should still ladle easily.

Ingredients

Żur kujawski

500 ml refrigerated fermented rye żur zakwas, stirred or shaken thoroughly before measuring
1.5 l water
500 g potatoes, peeled weight, cut into 2 cm cubes
120 g smoked bacon, cut into small lardons
200 g fully cooked smoked pork sausage, sliced
100 g yellow onion, finely diced
6 g garlic, about 2 cloves, finely chopped
2 bay leaves
4 whole allspice berries
1.5 g freshly ground black pepper
4 g dried marjoram, rubbed between your fingers
120 ml pasteurized sour cream, 18% fat
Fine salt, only after tasting; add a little if needed
Fresh marjoram, optional for serving

Method

Directions

Prepare the ingredientsCut the bacon into small lardons, dice the onion, chop the garlic and slice the fully cooked sausage. Cut the peeled potatoes into even 2 cm cubes. Keep raw bacon separate from ready-to-eat ingredients; wash your hands, knife and board after handling it.
Render the bacon and soften the onionSet a heavy-bottomed pot over medium heat. Add the bacon and cook for 6–8 minutes, stirring, until browned and its fat has rendered. Add the onion and cook for 5–7 minutes until soft. Stir in the garlic for 30 seconds without letting it brown.
Simmer the potatoesPour in 1.5 l water. Add the potatoes, bay leaves and allspice. Bring to a boil, then reduce the heat and simmer gently for 15–20 minutes, until a knife slides easily into a potato cube.
Add and cook the zakwasShake or stir the refrigerated zakwas until the settled rye flour is evenly suspended. Pour it into the pot gradually while stirring. Return the soup to a gentle simmer and cook for 8–10 minutes, stirring the bottom of the pot, until opaque, lightly thickened and clearly sour. Do not let the rye solids catch.
Heat the sausage and seasonAdd the sliced fully cooked sausage and simmer for 5 minutes, until steaming hot throughout. Remove the bay leaves and allspice berries. Rub the dried marjoram between your fingers and stir it in with the black pepper.
Temper the sour cream and serveWhisk the sour cream in a bowl with a ladleful of hot soup. Take the pot off the boil and stir the tempered cream back in. Taste before adding salt because the zakwas and cured pork vary in sodium. Serve hot, topped with optional fresh marjoram.

Nutrition per serving

Energy405 kcal
Carbohydrate35 g
Protein16 g
Fat23 g
Fibre4 g
Sodium1,250 mg
Allergensrye (gluten-containing cereal), milk

Estimated for one of six equal bowls: These ingredient-based values are estimates, not laboratory analysis. The sodium in packaged zakwas, bacon and sausage varies by brand, as do serving volume and the amount of rendered bacon fat retained in the soup.

Serving, make-ahead, and storage: Ladle one 400–450 ml bowl per person, making sure each serving includes potatoes and some smoked pork. The soup should be thick but pourable, opaque and distinctly sour from the rye zakwas. Bread is a suitable accompaniment; potatoes may also be cooked separately in other household versions.

Serving, make-ahead, and storage: You can cut the vegetables and meat ahead and refrigerate them separately in covered containers. Keep the packaged zakwas refrigerated and follow its use-by date and after-opening instructions. For a smoother texture when freezing, leave out the sour cream and temper fresh cream into the reheated soup.

Serving, make-ahead, and storage: Serve promptly or hold the soup at or above 60 °C. Refrigerate leftovers within two hours, or within one hour if the room is above 32 °C. Cool in shallow covered containers, store at or below 4 °C and use within four days. Reheat while stirring until 74 °C throughout. Add a small splash of water if the soup has thickened; if stored without sour cream, temper and add it after reheating. Freeze airtight portions for best quality within two months and thaw in the refrigerator; the potatoes may soften slightly.

Frequently asked questions

What makes Żur kujawski distinct?

Its common base is sour fermented rye zakwas, which gives the soup its characteristic tang and opaque, thick texture. Regional households varied the meat, enrichment and accompaniments, so no single measured formula represents every version.

Can I use vinegar or lemon juice instead of rye zakwas?

No. Fermented rye zakwas is the defining base of this soup; vinegar or lemon would make a different preparation. Look for a refrigerated Polish product labeled for żur or żurek.

Why do I need to stir the zakwas before measuring?

Rye flour settles during storage. Shaking or stirring redistributes it so the soup receives both the fermented liquid and the flour that gives it body.