Polish Żurek is a soup traditionally prepared for Easter. In some Polish families White Borsch is cooked instead of Żurek, the difference is Kvas/ sourdough that is used. For Żurek- rye sourdough, for Borsch – wheat sour starter.
If you plan to cook traditional Polish Sour Soup Żurek, you need a rye sourdough. You can buy one in Polish store or – I encourage you to- make one at home. It takes few days for the fermentation to make it job, so few days before making Żurek, follow these instructions: http://cookinpolish.com/sourdough-for-sour-soup-zakwas-na-zurek/.
Sourdough is a basic ingredient of Żurek, traditional Polish soup, prepared for Easter. It can be also called: kvas or sour starter, and is made by fermenting rye (for Żurek) or wheat (for White Borsch) flour. The process is easy, although you need few days to have your own homemade sour starter.
There is a whole variety kinds of sourdough, that you can prepare and use for soups, it depends on the flour you use. I prefer oatmeal one, because you can get very fresh flour on the spot- all you need to do is to grind oatmeal in an old coffee mill:) If you plan to make Żurek, use rye flour and follow the instructions below.