Kyselo is a hearty Czech sourdough soup which originated in Krkonoše mountains. The base of the soup is sourdough, usually made with fermented rye flour, poured in a caraway-spiced broth, and cooked until thickened. Even though there are numerous regional varieties, most versions are cooked with potatoes and mushrooms and served with scrambled or boiled eggs on top.

Closely resembling traditional Polish žur, kyselo is one of the oldest Czech dishes often enjoyed as a satisfying main course.