Sichuan pao cai (泡菜, literally soaking vegetable) is the traditional water-pickled vegetable preparation of Sichuan province — distinct from the vinegar-brined pickles of Western tradition and from the salt-packed kimchi of Korea. Vegetables are submerged in a brine of salt, sugar, Sichuan peppercorns, dried chillis, fresh ginger, and sometimes baijiu (白酒, Chinese spirits) in a sealed ceramic crock with a water-filled rim that allows gases to escape while preventing outside air from entering. The active fermentation is driven by naturally occurring lactobacillus bacteria on the surface of the vegetables. A well-established Sichuan pao cai crock — called a mother jar (坛母) — is a living culture that can be maintained indefinitely.
The brine: 1L water, 40g salt (non-iodized — iodine inhibits lacto-fermentation), 1 tbsp sugar, 1 tbsp baijiu, 1 tbsp Sichuan peppercorns, 3 dried chillis, 3 slices of fresh ginger. Bring water to a boil, dissolve salt and sugar, cool completely. Add peppercorns, chillis, ginger, and baijiu. The crock: Traditional Sichuan pao cai crocks have a water-sealed rim (shui tan, 水坛) — the lid sits in a channel filled with water, creating an anaerobic environment that allows fermentation gases to bubble out while preventing oxidation. This design is specific to Sichuan and allows a continuous top-off fermentation. Fermenting times: Depending on room temperature and vegetable: radish (2-3 days), cabbage (3-5 days), long beans (2-3 days), chilli peppers (1-2 weeks). The texture moves from crisp to pleasantly tender. Optimum flavour is pleasantly sour with background heat — never harshly acidic. Using pao cai in cooking: Pao cai vegetables are used as garnish, as cooking ingredients (particularly pao cai chilli, known as pao jiao 泡椒, in fish dishes and yu xiang preparations), and as a palate cleanser with meals.
Using iodized salt: Iodine kills the lacto-fermentation bacteria. Always use non-iodized salt. Introducing raw wooden utensils into the crock: Wood harbors competing bacteria that can spoil the ferment. Use only clean ceramic or stainless steel utensils.
Fuchsia Dunlop, The Food of Sichuan (2019); Fuchsia Dunlop, Every Grain of Rice (2012)