Fermented flour for a soup? Yes, that is possible in Poland. It is one of the most surprising, tastiest and most old-fashioned soups in Poland. The ubiquitous żurek is prepared in countless regional variations. It is typical Polish comfort food even nowadays, regardless of profession and social status. The soup is made with sour rye flour. Sour rye is a naturally fermented liquid mixture of water, spices and rye flour.
It may be bought in bottles in food stores, but it is easy to make it at home. Put rye flour in a large jar, mix with water, spices and cover with a clean cloth allowing access to fresh air. During the boiling process, the soup will thicken a bit because of the flour. What Poles add to the soup depends on their habits and will vary with the region: smoked bacon, meat, cubed or mashed potatoes, hard-boiled eggs, dried or pickled mushrooms, but also a specific tasty, aromatic pork sausage called 'white sausage' (biała kiełbasa). The soup is traditionally served at Easter. A vegetarian version is quite frequently served on Christmas eve: it is prepared with dry forest mushrooms, sometimes horseradish, potatoes and eggs. There exists a famous local variation: white borscht – similar to żurek, but using fermented wheat flour or zalewajka – is a certified regional speciality from central Poland.
Beetroot soup (barszcz czerwony)

Beetroot soup (barszcz czerwony) with uszka, photo: Katarzyna Klich / East News