Sushi originated in ancient China as a method of preserving fish by fermenting it in rice for months. The Japanese later adapted the dish, using rice vinegar to accentuate the sourness and shorten the fermentation process. Modern sushi varieties developed, including nigiri featuring seafood pressed over rice and maki consisting of fillings rolled in seaweed and rice. To make basic salmon sushi, short-grain rice is cooked, seasoned with rice vinegar, and spread over dried seaweed sheets along with salmon slices before being rolled up.