Chinkiang vinegar (镇江醋, Zhenjiang hei cu, Zhenjiang black vinegar) is China's most celebrated vinegar — a dark, complex, aged rice vinegar produced in Zhenjiang city in Jiangsu province. It is the vinegar referenced in classical Chinese recipes when a recipe calls for 'vinegar' without further specification in the Jiangnan tradition. Unlike Western red wine vinegars or Italian balsamic, Chinkiang vinegar is made from glutinous rice fermented with a wheat bran and water mixture, then aged in clay jars for 3-6 months. The result is a vinegar that is dark (nearly black), mellow, slightly sweet, with a complex earthy-fruity depth far beyond simple sourness. It is the essential dipping sauce for crab, for dumplings (jiaozi), for xiao long bao (where it cuts through the richness of the pork soup), and for cold dishes.
Culinary uses: Dipping for dumplings: 3 parts Chinkiang vinegar, 1 part light soy, 1 tsp finely julienned fresh ginger — the classic Chinese dumpling dipping sauce. In cold dishes (liang cai): Chinkiang vinegar is the sourness component in fish-fragrant sauce (yu xiang), in cold noodle dressings, and in many Sichuan and Hunan cold preparations. In braises: A small amount added to a braise late in cooking brightens and elevates the flavour without producing an identifiable sourness. In sauces: The sweetness and complexity of Chinkiang vinegar suits Chinese sauces better than sharper Western vinegars. Substitution: Balsamic vinegar (not aged — supermarket-quality) is the most frequently recommended Western substitute — it shares the dark colour, mellow sourness, and slight sweetness. A combination of balsamic and rice vinegar is even closer.
Fuchsia Dunlop, Every Grain of Rice (2012); Fuchsia Dunlop, Land of Fish and Rice (2016)