Kwas
Here are recipes for Kwas that is used for Polish breads and soups.
Rye Kwas
75 g rye flour
600 ml water
A small clove of garlic finely chopped.
Add everything to a non metallic container and mix to uniformly combine.
Cover with a piece of cloth and let it ferment in a warm place for 4 to 5 days.
Drain off the liquid.
Beet Kwas
Peel and chop 2 large beets.
Add water to cover.
Add everything to a non metallic container.
Add half a slice of sour dough rye bread or a tablespoon of sourdough or undrained rye Kwas. If you have neither, finely chop a small potato, with skin, and add it.
Cover with a piece of cloth and let it ferment in a warm place for 4 to 5 days.
Drain off the liquid.
Here are some good videos and below that links to many Polish food recipes.
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