Lenten Sour Rye Soup with Herring

Żur Postny ze Śledziem

Żur (pron. ‘zhur’; just like in the French word ‘jour’) is the essence of Polish cuisine. It’s both the name for the fermented rye starter; as well as for the soup itself (that’s soured with it).

In this old-Polish recipe, Żur is brewed on vegetable stock, generously soured with sharp rye starter and topped with some crunchy roasted parsnip.

Just like in the olden days, the soup is served with some meaty herring fillets, for that extra, fishy ‘oomph’.

This recipe is the part of the “Old-Polish Fast” series, in which we time-travel back to an old-Polish kitchen.

For the full list of ingredients & detailed instructions, please see the recipe card at the end of this post. But before you scroll, there’s important stuff to know below.

Throughout centuries, Sour Rye Soup was a staple of the Polish diet. That’s because it was flavourful and nutritious, while still affordable, even among the poorest of the poor.

‘Żur’ was especially enjoyed during fasting days, sometimes enriched by some fish meat – mostly herring. Those with deeper pockets would go for more expensive northern pike, sturgeon or carp instead – either fresh, smoked or dried.

I found this recipe in a publication called “Kanon Kuchni Polskiej” (“the Canon of Polish Cuisine”), published recently by the National Institute of Rural Culture and Heritage.

Its digital version is available (in Polish) here.

Do you need any special ingredients to make this Lent Żur Soup with Herring?

Yes. There’s one crucial ingredient that cannot be easily substituted – Fermented Rye Flour Starter (in Polish: ‘Zakwas Żytni’).

🇵🇱 In Poland, it’s sold in food stores, at farmer’s markets and in some bakeries.

Fermented Sour Rye Starter (Zakwas) in a bottle

🌍 Sadly, Fermented Rye Starter outside of Poland is hard to come by. But on occasion, it should be available at a Polish Deli, especially in the time leading to Easter. Some expat homecooks try to replace it with vinegar, but that really spoils the magic.

Luckily, it’s easy to make at home. In essence, it’s like a watered-down rye sourdough starter.

fermented rye starter

If you’re a home baker yourself, this process will be familiar to you.

Here’s a detailed recipe for a homemade Sour Rye ‘Zakwas’ (👈 click for a recipe).

What should you serve with this Lent Sour Rye Soup?

Sour rye soups are usually served as a first course, therefore are rarely paired with any sides, other than a slice of fresh rye bread. 

Can you make this Sour Rye Soup another way?

This recipe follows the rules of the old-Polish fast, meaning: no meat and no dairy (but fish is allowed). That’s why here, the soup is served with roasted parsnips and herring fillet pieces.

Parsnips can be swapped for another vegetable, such as turnips or parsley root. Other local recipes call for dried mushrooms (soaked in advance and added to the stock).

In some regions of Poland, Żur soups contain potatoes as well – roasted, boiled or mashed. 

If you enjoy both meat and dairy, try this classic Easter Żurek recipe. It’s served with boiled egg and white kiełbasa sausage

What diets is this Lent Żur suitable for?

This recipe is meat-free (but please note that it’s served with herring). If you use some vegan sour cream to serve, this soup is dairy-free as well.

How long can you keep this Sour Rye Soup in the fridge?

Once you’ve put it out, ideally you should eat it within 4 hours.

If you allow any leftovers to cool, make sure to refrigerate in a container with a lid and chill.  You can keep leftovers of Carrot, Orange and Thyme Soup in the fridge for 1-2 days.

Can I freeze this Lent Sour Rye Soup?

Yes, this recipe can be frozen, but I would avoid freezing it together with herring pieces.

Freeze the soup as soon as it’s cold enough to do so. Use a container or bag that is freezer-friendly. Don’t forget to add a label with a description and the date. Aim to consume within 2-3 months.

How do I reheat this soup?

From chilled: Place the soup in a microwave-friendly container, cover it with a loosely fitting lid. Heat for 4-7 minutes, until piping hot throughout. Alternatively, reheat it on the stove. Bring to a near-boil, then reduce to a simmer, and cook for another 2-3 minutes.

From frozen: Allow the soup to thaw first. Reheat in the microwave (covered) for 3-5 minutes; then stir. Cook for a further 5 minutes until piping hot.

Smacznego!

Żur (Fermented Sour Rye Soup) served with herring
Żur (Sour Rye Soup) with Herring

Lent Sour Rye Soup with Herring

Yield: 8
Prep Time: 10 minutes
Cook Time: 40 minutes
Total Time: 50 minutes

Ingredients

  • 7 oz (200 g) salted herring fillets, soaked in water or milk
  • 1.1 lb (500 g) parsnip root, peeled
  • 1 tbsp canola oil
  • ½ lemon
  • 6 ups (1.5 lq quart, 1.5 litre) vegetable or fish stock
  • 2 ¼ cups (500ml) Sour Rye Flour Starter (link to a recipe in the notes)
  • 1 bay leaf
  • 3-4 allspice berries
  • 1 tsp caraway seeds, ground
  • Pinch of salt
  • Pinch of black pepper, ground
  • 5 tbsp sour cream, optional; can be substituted with almond sour cream

Instructions

  1. [The night before] Soak salted herring fillets in water or milk overnight, making sure they’re completely covered.
  2. Peel parsnips and dice them into cubes, roughly 1/2-inch (1.3-1.5 cm) thick. Move them onto a baking tray and shower with a juice of half lemon and a tablespoon of canola oil.  Bake for 30 minutes in 340°F (170°C). [I’m using a non-stick baking tray - but if you use a regular one, it’s worth greasing it with a drop of olive oil, or line it with baking paper.] 
  3. Bring the vegetable stock to a boil, then reduce the heat to a simmer. 
  4. Gradually pour in the fermented rye starter (both flour and liquid) and taste as you go. I add the full 500 ml portion, but if you’re sensitive to sour flavours - perhaps  three-quarters of the rye starter will be enough? 
  5. Add in the spices: bay leaf, allspice berries, ground caraway seeds, a pinch of salt and pepper. Continue cooking on a low heat for another 5-10 minutes.
  6. Drain the excess water (or milk) off the herring fillets, and cut them into smaller pieces.
  7. Serve the soup with roasted parsnip, herring pieces and garnish with a dollop of almond sour cream (optional).

Notes

  • I've adapted this recipe from "Kanon Kuchni Polskiej" (“the Canon of Polish Cuisine”), published by the National Institute of Rural Culture and Heritage.
  • Nutrition Information:
    Yield: 8 Serving Size: 1
    Amount Per Serving: Calories: 445Total Fat: 21gSaturated Fat: 5gTrans Fat: 0gUnsaturated Fat: 13gCholesterol: 106mgSodium: 455mgCarbohydrates: 27gFiber: 5gSugar: 2gProtein: 38g

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    Cuisine: Polish
    Region / Subregion: all-Polish
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