【Reading】はやすし/はややずし、いちやずし

【English Name】Haya sushi / Haya zushi

Hayazushi (early sushi) refers to sushi made by a method that imparts a sour taste in a short time using vinegar, in contrast to the ancient nare-zushi (fermented sushi), which required several months of lactic-acid fermentation.
In nare-zushi, fish and rice are pickled together for a long period and allowed to ferment naturally, but in hayazushi, rice vinegar or lees vinegar is mixed into the rice, omitting the fermentation process and greatly shortening the preparation time. This technique is said to have spread from the mid-Edo period onward and is the direct predecessor of today's nigiri sushi and chirashi sushi.

Ichiya-zushi (one-night sushi) is a semi-fermented type of sushi in which the pickling time is limited to roughly one night. Standing between nare-zushi and hayazushi, it is characterized by combining the distinctive flavor of light fermentation with the freshness of the ingredients themselves. In some regions it has been handed down as a festive or New Year's celebratory dish.

In the history of sushi, the transition from nare-zushi to ichiya-zushi and then to hayazushi using vinegared rice is regarded as an important shift, marking the change from preserved food to food enjoyed for taste.