 The Slavs collected hogweed in May and used its roots for stewing with meat , while the stems , leaves and umbels were chopped , covered with water and left in a warm place to ferment . After a few days , lactic and alcoholic fermentation produced a mixture described as " something between beer and sauerkraut " . This concoction was then used for cooking a soup characterized by a mouth @-@ puckering sour taste and pungent smell . As the Polish ethnographer Łukasz <unk> wrote in 1830 , " Poles have been always partial to tart dishes , which are somewhat peculiar to their homeland and vital to their health . " 
