Żurek (Polish Sour Rye Soup)

Ingredients

• 1 cup (120g) coarse rye flour, for the starter
• 2 cups (475ml) lukewarm filtered water, for the starter
• 3 cloves garlic, crushed, for the starter
• 1 bay leaf, for the starter
• 4 whole allspice berries, for the starter
• 6 cups (1.4L) chicken or pork stock, preferably made with smoked bones
• 1.5 lbs (700g) raw biała kiełbasa (Polish white sausage), whole
• 4 oz (115g) smoked bacon, diced
• 4 medium potatoes, peeled and diced
• 1 small onion, diced
• 3 cloves garlic, minced
• 1 tsp dried marjoram
• 4 hard-boiled eggs, halved
• 1/2 cup (120ml) heavy cream or sour cream
• salt and white pepper, to taste
• fresh grated horseradish, for serving (optional)
• 4 small round rye loaves, hollowed out, for serving (optional)

Before you cook

• Five days before you plan to serve the soup, whisk the rye flour and lukewarm water together in a clean glass jar
• Add the crushed garlic, bay leaf, and allspice berries to the jar
• Cover the jar loosely with a linen cloth or gauze and set it in a cool, dark spot away from direct sun
• Stir the starter twice a day for 5 to 7 days, until it smells pleasantly sour like a tangy pickle brine
• On the day of cooking, dice the bacon, potatoes, and onion
• Mince the garlic for the soup
• Boil the eggs, cool them under cold water, peel, and halve them
• If making bread bowls, slice the tops off the rye loaves and hollow out the centers, leaving a sturdy shell

Steps

1. Render the diced bacon in a large soup pot over medium heat until the fat runs and the edges crisp, about 5 minutes
2. Add the diced onion to the pot and cook, stirring, until translucent, about 4 minutes
3. Pour in the stock and bring it to a gentle simmer
4. Slide the whole raw kiełbasa into the simmering stock and poach it for 15 minutes
5. Lift the kiełbasa out of the pot, let it cool for a few minutes, then slice it into rounds and set it aside
6. Add the diced potatoes to the simmering stock and cook until just tender, about 12 minutes
7. Strain the zakwas through a fine sieve directly into the pot, pressing on the solids to extract all the sour liquid, then discard the spent flour
8. Stir the minced garlic and marjoram into the pot
9. Simmer the soup gently for 10 minutes, stirring occasionally so the bottom doesn't catch, until it thickens slightly
10. Return the sliced kiełbasa to the pot and warm it through for 2 minutes
11. Season the soup with salt and white pepper
12. Take the pot off the heat and stir in the cream until fully incorporated
13. Ladle the soup into bowls or into the hollowed rye loaves
14. Top each serving with a halved hard-boiled egg and a little grated horseradish if using