Name: Łubnicki Milk-and-Buttermilk Soup with Cracklings (Łubnicki żur smażony)
Prep time: 15 min
Cook time: 35 min
Total time: 50 min
Yield: 6 servings
Cuisine: Polish
Ingredients: 100 g fresh, unsalted pork backfat with minimal lean, diced small; 800 ml pasteurized whole milk, divided; 800 ml pasteurized cultured buttermilk; 80 g plain wheat flour; 1.2 kg waxy potatoes, scrubbed and left whole; Up to 4 g fine salt, to taste; 1 g freshly ground black pepper

Wide breakfast table with creamy Łubnicki soup, pork cracklings and a separate bowl of boiled potatoes.

Yield 6 servings

Serving about 265 ml soup plus 200 g skin-on potatoes

Active preparation about 15 minutes

Cooking time about 35 minutes; potato boiling overlaps with soup preparation

Ingredients ↓

At a glance

Łubnicki Milk-and-Buttermilk Soup with Cracklings (Łubnicki żur smażony)

Łubnicki żur smażony is a thick, gently tangy soup from Łubnice in Łódź Voivodeship. It combines sweet milk with cultured buttermilk, wheat flour and crisp pork cracklings. Skin-on boiled potatoes are served alongside, ready to peel or break into the soup at the table.

The name includes żur, but this Łubnice preparation is not the familiar rye-sourdough soup called żurek. Its pale, creamy base comes from milk and buttermilk; the rendered pork fat and cracklings give it the “smażony” character. The Polish Ministry of Agriculture lists the dish among Łódzkie’s traditional products, and the local account traces it in Łubnice for at least three generations.

This measured home version keeps the listed ingredients and simple seasoning while making the amounts practical for six servings. A little wheat flour is cooked in the rendered fat, then milk and buttermilk are whisked in for a smooth, spoon-coating texture. Warm it gently so the cultured dairy stays creamy. Serve the potatoes separately, as is customary, and let each person decide how much to add to the bowl.

Tips for the best result

Choose fresh, unsalted pork backfat with little lean meat. Smoked bacon or cured lard would change the dish’s simple dairy flavor.
Keep the backfat cold while dicing it into small, even pieces; they render more evenly than large chunks.
Start the fat in a cool, dry skillet over medium-low heat. Gentle rendering gives you clear fat and crisp cracklings without smoking.
Stir the flour into the rendered fat and cook it briefly. This cooks away the raw-flour taste and helps thicken the soup.
After cooking the flour in fat, take the pan off the heat and whisk in cold milk gradually until smooth.
Add the slurry gradually while whisking, scraping the bottom and corners so the thickening base does not catch.
Use pasteurized milk and cultured buttermilk straight from the refrigerator; keep both cold until needed.
Once the buttermilk is in the pot, warm the soup over low heat and avoid a rolling boil, which can make cultured dairy look grainy.
Taste before adding all the salt. Cracklings and dairy vary, so the full amount may not be necessary.
Boil the potatoes whole and with their skins on. They are served separately, not stirred into the soup before serving.

Ingredients

Soup and potatoes

100 g fresh, unsalted pork backfat with minimal lean, diced small
800 ml pasteurized whole milk, divided
800 ml pasteurized cultured buttermilk
80 g plain wheat flour
1.2 kg waxy potatoes, scrubbed and left whole
Up to 4 g fine salt, to taste
1 g freshly ground black pepper

Method

Directions

Boil the potatoes.Put the scrubbed, whole potatoes in a saucepan and cover with fresh water. Bring to a boil, then simmer for about 20–25 minutes, depending on size, until a knife enters easily. Drain and keep hot while you make the soup.
Render the backfat.Cut the cold backfat into small dice. Put it in a wide, cool skillet and set over medium-low heat. Stir often for about 10–15 minutes, until the fat is clear and the cracklings are crisp and lightly golden. Do not let the fat smoke. Keep both the cracklings and rendered fat in the skillet.
Cook the flour.Transfer about 30 g of the rendered fat to the heavy soup saucepan. Stir in the flour over medium-low heat for 1–2 minutes, keeping it pale, until the raw-flour smell fades. Take the pan off the heat and gradually whisk in 200 ml cold milk until smooth. Whisk in the remaining rendered fat and the remaining 600 ml milk.
Thicken the milk base.Set the pan over medium-low heat and whisk constantly until the mixture is steaming. Cook gently for 2–3 minutes, stirring across the bottom, until thickened and no raw-flour taste remains. Do not let it scorch or boil.
Add the buttermilk.Pour in the cultured buttermilk gradually while whisking. Warm over low heat, stirring, until the soup is steaming hot throughout; do not let it reach a rolling boil. Fold most of the cracklings into the soup, reserving some for the table.
Season and check the texture.Add freshly ground black pepper and begin with a small pinch of salt. Taste, then add more only if needed. The soup should be thick enough to coat a spoon but still pour easily; whisk in a splash of milk if it becomes too thick.
Serve hot.Ladle the soup into warm bowls and scatter the reserved cracklings over the top. Bring the hot potatoes to the table separately so diners can peel them or break them into their own bowls.

Estimated nutrition per serving

Energy490 kcal
Carbohydrate56 g
Protein16 g
Fat24 g
Fibre4 g
Sodium470 mg
Allergensmilk and wheat/gluten; contains pork

The rounded estimate covers one sixth of the soup and potatoes and uses general food-composition data. Pork backfat yield and dairy brands affect fat and calories; sodium includes the full 4 g salt allowance, so the actual amount may be lower.

Serving, storage, and make-ahead: Serve the soup hot with the potatoes on a separate plate or in a bowl. A spoonful of potatoes can be broken into the soup at the table; keeping them separate preserves the dish’s customary presentation and lets everyone choose their portion. The soup is best just made, but you can dice the backfat and scrub the potatoes earlier in the day; keep both refrigerated until cooking. Do not leave the finished soup at room temperature for more than 2 hours, or more than 1 hour when the air is above 32°C. Cool leftovers promptly in shallow containers and refrigerate at 4°C or colder within 2 hours. Use within 2 days. Reheat only the portion you need, stirring until it reaches 74°C; avoid repeated reheating because the dairy can separate. Freeze only if necessary; the texture may be grainier after thawing.

Frequently asked questions

Is this the same soup as żurek?

No. Despite żur in the name, the Łubnice version described here uses sweet milk and sour cultured buttermilk, thickened with wheat flour. It does not use fermented rye starter.

What are “w dłubinkach” potatoes?

The name refers locally to potatoes boiled in their skins. Scrub them well, boil them whole, and serve them beside the soup so each person can peel or break them into the bowl.

Can I use bacon instead of fresh backfat?

Fresh unsalted backfat is closer to the traditional ingredient profile. Smoked or cured bacon adds salt and smoke that can overwhelm the mild, tangy dairy base.

To finish

Render the fresh backfat slowly, cook the flour briefly in the fat, and whisk in pasteurized milk and buttermilk for a smooth, gently tangy soup.
Serve it hot with whole skin-on boiled potatoes and crisp cracklings; refrigerate leftovers promptly and use within 2 days.