Dongbei suan cai

Step 1: Remove any damaged outer leaves from the 2 napa cabbages, trim the root end but keep the head intact, and cut each cabbage in half lengthways.

Step 2: Scrub a 5–6 litre ceramic crock or food-grade bucket and a plate that fits inside it with hot soapy water, then rinse with boiling water. You also need a weight: a clean stone or a sealed bag of brine.

Step 3: Bring a large pot of water to a boil. Holding each half by the root, dip it into the water for 30–60 seconds, until the leaves soften and turn bright, then let it drain and cool on a rack.

Step 4: Dissolve 2 ⅛ oz salt in 3 litres cool boiled water to make a brine of 2% salt (20 g per litre). Pack the cabbage halves tightly into the crock, alternating root ends, pressing down so there are few gaps.

Step 5: Pour over the brine to cover the cabbage by at least 3 cm, put the plate on top and weigh it down so nothing floats. Cover the crock loosely with a lid or cloth.

Step 6: Leave in a cool place, ideally 10–64°F, for 3–4 weeks. Check every few days: bubbles, cloudy brine and a sour smell are normal; skim off any flat white film, and top up with 2% brine if the level drops. Discard if you see fuzzy coloured mould, pink or black patches, or smell rot.

Step 7: It is ready when the leaves are pale and translucent and taste sour right through, after at least 3 weeks; do not eat it earlier. Transfer to clean jars, keep covered by brine in the fridge, and use within 2 months. Shred finely and rinse before cooking.