Equipment
* optional
Ingredients
Aromatics and Base
- 30 g unsalted butter
- 400 g smoked kielbasa, cut into half-moons
- 150 g leek, white and light green parts only, thinly sliced and washed
- 150 g yellow onion, finely diced
- 4 garlic, minced
Vegetables and Broth
- 1500 ml chicken stock, hot or warm
- 400 g waxy potatoes, peeled and diced into 1.5cm cubes
- 3 g dried marjoram, crushed between fingers
- 2 bay leaves
- 10 black peppercorns, whole
Thickener and Tang
- 100 g stale sourdough bread, crusts removed, torn into small pieces
- 150 g creme fraiche, room temperature
- 15 ml apple cider vinegar
Garnish
- 3 eggs, hard-boiled and halved
- 10 g fresh dill, finely chopped
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 487 kcal
- Protein
- 17 g
- Carbohydrates
- 33 g
- Fat
- 32 g
- Fiber
- 3 g
- Sugar
- 6 g
- Sodium
- 1872 mg
- Saturated Fat
- 13 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 12 g
- Polyunsaturated Fat
- 5 g
- Cholesterol
- 172 mg
- Potassium
- 713 mg
- Calcium
- 125 mg
- Iron
- 3.0 mg
- Magnesium
- 47 mg
- Phosphorus
- 276 mg
- Zinc
- 1.9 mg
- Vitamin A
- 140 mcg
- Vitamin C
- 30 mg
- Vitamin D
- 1.1 mcg
- Vitamin E
- 1.1 mg
- Vitamin K
- 17 mcg
- Vitamin B6
- 0.4 mg
- Vitamin B12
- 0.8 mcg
- Thiamin
- 0.25 mg
- Riboflavin
- 0.50 mg
- Niacin
- 4.0 mg
- Folate
- 48 mcg
- Water
- 416 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
Melt the butter in a heavy-bottomed pot over medium heat. Add the sliced kielbasa and sear until deeply browned and the fat has rendered into the pot, about 8 minutes. Remove the kielbasa with a slotted spoon and set aside, leaving the fat in the pot.
Lower the heat slightly. Add the sliced leek, diced yellow onion, and a pinch of salt to the rendered fat. Sweat the vegetables until completely soft and translucent, stirring occasionally, for about 10 minutes. Add the minced garlic and cook for 1 more minute until fragrant.
Add the diced potatoes, chicken stock, crushed marjoram, bay leaves, and black peppercorns to the pot. Bring the mixture to a gentle boil at 100°C/212°F, then immediately reduce the heat to maintain a steady simmer at 90°C/195°F.
Cover the pot and let simmer until the potatoes are completely tender and easily pierced with a fork, approximately 15 to 20 minutes.
While the soup simmers, place the torn sourdough bread pieces and room-temperature creme fraiche into a heatproof bowl. Once the potatoes are tender, ladle about 250ml of the hot soup broth into the bowl. Use a whisk or immersion blender to process the mixture until it becomes a completely smooth, velvety slurry.
Slowly pour the bread and creme fraiche slurry back into the soup pot while stirring continuously. Return the seared kielbasa to the pot. Let the soup gently simmer for 5 more minutes to thicken and allow the flavors to meld. Do not let it boil vigorously.
Remove the pot from the heat. Discard the bay leaves. Taste the broth; it should have a distinct, bright tang from the sourdough and dairy. If it needs more acidity, stir in the optional apple cider vinegar. Adjust salt and pepper to taste.
Ladle the hot soup into warmed bowls. Garnish each portion with half of a hard-boiled egg and a generous sprinkle of fresh chopped dill.
Chef's Notes
- The depth of flavor in this soup relies entirely on the quality of your kielbasa. Look for heavily smoked, naturally cased Polish sausages from a butcher rather than mass-market brands.
- Marjoram is the backbone herb of Polish cuisine. Rubbing the dried herb between your fingers before adding it to the pot releases its essential oils, maximizing its sweet, piney aroma.
- If you want to make this even more traditional, a spoonful of prepared grated horseradish stirred directly into the bowl at serving time provides an incredible pungent kick that cuts through the rich broth.
- The sourdough bread acts as a rapid shortcut for 'zur' (fermented rye flour starter). Removing the crusts ensures the soup maintains a creamy, pale color without dark flecks.
Storage
Refrigerator: 4 days — Flavors will deepen and meld overnight, making it an excellent leftover.
Freezer: 2 months — Texture of the potatoes may change slightly upon thawing. Reheat gently.
Reheating: Reheat on the stovetop over medium-low heat. Do not bring to a rapid boil to prevent the dairy from separating.
Troubleshooting
Soup is too thin and lacks body
Cause: Sourdough bread was too light or airy, failing to release enough starch.
Fix: Use a fork to mash some of the potatoes directly against the side of the pot, or blend an additional small piece of bread with hot broth and stir it in.
Prevention: Weigh the bread precisely and use a dense, rustic loaf.
Broth lacks the characteristic sour bite
Cause: The sourdough bread was not fermented long enough or was too mild.
Fix: Stir in 15ml of apple cider vinegar, white wine vinegar, or even dill pickle brine off the heat until the desired tang is reached.
Prevention: Source a strongly fermented sourdough, or rely on traditional fermented rye starter (zur).
Creme fraiche appears grainy in the soup
Cause: The soup was boiled vigorously after adding the dairy, or the dairy was added while ice cold.
Fix: Cannot be completely fixed texturally, but blending the soup slightly off the heat can help re-emulsify the fat. The flavor will remain excellent.
Prevention: Always temper the creme fraiche with hot broth and maintain a gentle simmer (below boiling) once dairy is incorporated.
Cultural Context
White borscht, frequently associated with the Polish classic Zurek, is historically built on a foundation of fermented liquid known as zur. This accessible variation captures that signature earthy tartness by utilizing torn sourdough bread and creme fraiche. While traditionally central to Easter morning feasts to break the Lenten fast, its deeply comforting, warming profile has cemented it as a celebrated staple throughout Eastern Europe's long winter months.
