What we usually throw away in the trash, carefully wrapped in a bag and pressing our noses in it, is considered a national product by the Nordic peoples. We are talking about sauerkraut herring, which is preserved in a special way. The gutted fish, but with the caviar and appendix left in it, is salted and put into a dish to sour in the open air. At this time, the processes of fermentation and putrefaction occur, enzymes are released in the carcass and bacteria begin to multiply actively. After that the herring is placed in canning jars and left to sour for some more time. After opening the can, the herring exudes a highly specific aroma that appeals only to Swedes. For the untrained, the smell can make a person sick. Swedes enjoy surströmming sandwiches and serve it with boiled potatoes and green onions.