Fermentation time for the zur: 72 hours
Cooking time: About 1 hour

This typically Polish soup is often called "vigil soup,"

Every region has a distinctive version. The Cracow version (containing vegetables) is different from the versions from Kielce, Namyslow or Podlachie.

Masovia variation
To enhance the flavor, Masovians add horseradish and sour cream to the soup, as well as marjoram, garlic, finely chopped mushrooms and sliced white sausage. The resulting soup is slighly sour and straightfoward.

In every case, the basic ingredient is always a fermented rye flour mixture known as zur. 

Eaten on fast days, zurek was always a very frugal soup. Only essential ingredients were added. However, for Easter, it took on a much more celebratory note, with the addition of sliced sauge, fried bacon or halved hard-boiled eggs.

Variant for the zur
2 rye bread crusts
2 brown bread crusts
1 tsp. cumin

 Zur

1. Place the rye flour in an earthenware bowl and mix in the water.
2. Cover with a clean cloth and let ferment for 72 hours at room temperature. 
3. Stir the zur every day. After 72 hours, it should have a sour smell and taste. The yeast is ready.

Soup

1. In a soup pot, cook the vegetables in the boiling water. Remove and set aside (return them to the soup as in the Cracow version or serve them as a side dish with the main course).
2. Add the zur to the vegetable broth. Stir in the flour, dissolved in a little cold broth, to thicken the soup.
3. Bring to a boil and simmer to the desired consistency. Season with salt to taste. 
4. Serve with sausage slices, a little crushed garlic or marjoram, fried bacon cubes, or a halved hard-boiled egg.