Paocai (Sichuan Brine Pickles from a Perpetual Jar)

Variations

• Almost any vegetable. Daikon, carrot, cabbage, cauliflower, green chillies, long beans, cucumber, ginger, garlic. Watery ones like cucumber are ready in two days and go soft if left.
• Sichuan and elsewhere. ko.wikipedia notes Sichuan paocai as the famous one. Northeastern suancai is a different line — cabbage pressed down without a brine at all.
• Tiaoshui paocai. The quick "diving" version, pickled for hours or overnight: crisp, barely sour. It uses no jar, so it never builds a lao yan shui.
• As an ingredient. Mature paocai and its liquid are the sourness in suancai yu (fish soup) and in stir-fries. That is the real reason to keep an old jar.
• About the photograph. The hero is a dressed plateful, not the jar. Commons has essentially no photograph of a water-sealed paocai jar.

Tips

• The thing you are finishing is the brine, not the side dish. This is the whole page. It is not a pickle you make and throw away: you change the vegetables and keep the same brine for years. A jar whose lactic population is established ferments faster and more predictably. Which means the first batch is the worst one you will make — that is normal, not a failure.
• It answers Fermentation Basics' third lever with the vessel. That guide reduces keeping air out to "pressing everything under the liquid". Paocai does that and then adds a layer: water in the lid's moat, a one-way valve that lets gas out and no air back in. For comparison, Takuan answers the same lever with no liquid at all, a dry bran bed, and Lahpet removes the premise by pressing the liquid out of the leaves themselves. One lever, several answers.
• How it differs most from Kimchi. Kimchi salts the cabbage so that it makes its own liquor, then coats it in a paste. Paocai only immerses vegetables in a brine that was already there and that outlives them. Kkakdugi and Oi-sobagi belong to the kimchi side.
• One drop of oil kills the jar. Chopsticks, ladle, hands — nothing greasy goes in. A surface film is nearly always oil plus oxygen.
• The baijiu is a safeguard, not a flavour. The alcohol suppresses the wrong microbes early on, and a tablespoon is also the first aid when something starts to go wrong.
• Dry the vegetables completely. Water carried in drops the salt concentration, and under 5 percent you are in the band the guide describes where things go soft and the wrong organisms win.
• Crispness is about which part, not how long. Use the dense core of the daikon and the heart of the cabbage. Watery parts collapse within days.
• Adjust saltiness when you dress it. Keep the jar at 5 percent and rinse a piece briefly if it is too salty. Diluting the brine puts the whole jar at risk.