Akasu, or kasuzu (aka red vinegar) is experiencing a renaissance these days because Michelin-starred restaurants have really embraced it, but don't get it wrong, it's been around for a long time. Back when they first started making it, around 1800, it rose in prominence alongside the rise of sushi in Edo (the city that would become known as Tokyo) and it was the vinegar used to make sushi rice. Back then, the recipe was red vinegar and a touch of salt (no sugar!). That's because red vinegar is made with aged sake lees so it's very soft in acidity and rich in umami and just a pinch of salt brings out the gentle sweetness of the vinegar. You can use it to make sushi rice that stands up beautifully to richer flavored, oily, and fatty fishes (such as oh-toro or salmon) or cut it with regular rice vinegar and add sugar and salt to make milder sushi rice. You can also use it to make salad dressings or drizzle a little on sauteed vegetables to brighten the flavors. I often hear people compare the flavor to sherry vinegar. 

Akasu is a kasuzu, or vinegar made from kasu, or the lees left over after making sake. This one is made from the sake lees of high quality ginjo from Echigo prefecture. The lees are stored in wooden boxes to age for 3+ years while the lees undergo a gentle mallard reaction, the same process that aged wines, whiskeys, and cheeses go through. This reaction causes the proteins and starches to convert to amino acids (umami) and sugars and also produces a variety of flavor compounds that lead to complex flavors. After aging the sake lees, they are finally mixed with pristine Japanese water and then inoculated with a vinegar mother and fermented in wooden barrels for two to three months to make the red vinegar. The vinegar is further aged for two to four months in cedar barrels. 

Akasu is a dying art form since it requires so much aging. In fact, were it not for the support of Michelin restaurants, it may have already disappeared completely. Even now, there are fewer and fewer brewers making Akazu available to the public, so if this is the sort of product you'd like to see continue in the market, please support the industry by buying it and sharing knowledge of it with friends.

Made in Kamagaya, Chiba, Japan

6.8 fl oz (a small bottle, but you generally use it sparingly)