Sushi vinegar (sushi-zu) is rice vinegar seasoned with sugar and salt, used specifically to flavor the cooked rice in sushi; some recipes add mirin or kombu. It differs from plain rice vinegar in being pre-sweetened and salted for rice rather than general cooking use, and it gives sushi rice its characteristic sticky-yet-tender texture and mild sweet-and-sour edge. Seasoning rice with vinegar is generally thought to have developed in Japan as a faster substitute for the older method of preserving fish by fermenting it in rice for weeks or months (narezushi, a practice that still survives in a few regional dishes). Beyond sushi rice, it can be used as a marinade or a tangy dressing for seafood and vegetables.