Black vinegar is a broad umbrella term for a grain-based vinegar—sometimes aged for years and sometimes infused with flavor. Most black vinegars are aged for at least six months and up to several years, which gives them their signature color. Traditionally, they’re made in a similar process to balsamic, where the vinegar is aged in a container for years so that it develops a distinct level of complexity. The longer that it sits, the more complex the flavors become. The key differences between black vinegar and balsamic are that black vinegar is made with grains instead of grape juice and aged in clay pots instead of barrels. And whereas balsamic vinegar is made using liquid-state fermentation (only the grape juice is fermented), Chinese black vinegar is made by fermenting whole steamed grains.
Generally speaking, there are four major regional types in China: the northern Chinese province of Shanxi is known for vinegar made with sorghum, wheat, and barley. The city of Zhenjiang in southern China makes its, more commonly referred to as Chinkiang vinegar, with sticky rice. Sichuan has a black vinegar made with wheat bran and seasoned with a pungent medley of Chinese medicine spices. And finally, the province of Fujian in eastern China makes a glutinous rice vinegar infused with a special fungus that gives the final product more of a dark red hue than black.