Home-preserved mustard greens

Ingredientsserves 4

Equipment

• A crock or a food-grade bucket, and a plate with a jar of water on it as the weight
• Drying racks, or a clean flyscreen; and a balcony that gets the sun
• A steamer, for the 三蒸三曬
• The balcony is the equipment. This wants the dry sun of a Hong Kong winter, and a Sydney July can give it. A Melbourne one cannot, and there a dehydrator is the honest answer.

How the time splits

1. 2 daysSplit the heads and lay them in the sun until limphands off
2. 20 minSalt, rub, pack and presshands on
3. 20 daysUnder the weight, somewhere cool and darkhands off
4. 5 daysSqueezed out and dried in full sunhands off
5. 1 hrThree rounds of steaming and sunning, for the black sweet kindhands on

Method

1. Wash the greens, split each head in two or four, and lay them in the sun for a day or two until the leaves go limp.
2. Rub the coarse salt into the leaves, and rub hard — until they darken and start giving up water. Pack them into the crock in layers, salt and greens, pressing each layer down.
3. Put a plate on top and a jar of water on the plate. Every leaf must sit below its own brine; the ones that float are where the mould starts. Cover it and leave it somewhere cool and dark.
4. After seven to fifteen days it will smell sour and have turned yellow. That is already 酸菜 and you can cook with it. For 梅菜, keep it under the weight — twenty days is better.
5. Lift it out, squeeze it dry, and spread it in full sun for three to seven days, bringing it in at night. It is done when it is leathery and almost weightless: that is 梅乾菜.
6. For the black, sweet 惠州 kind: steam it fifteen minutes, rest it twenty, sun it for a day, and repeat three times. It darkens to a deep red-brown. Skip this and you have the salty kind, which is just as useful.
7. Store it bone dry in a sealed jar or a paper bag in the fridge. It goes darker with age, and that is oxidation, not spoilage.

Take care

• This is a lacto-ferment and two things keep it safe: every leaf stays under the brine, and the weight stays on top. Whatever sits above the waterline is where the mould starts. No metal lid on the crock. If you see fuzzy mould, throw the whole batch out rather than scooping that patch away. The salt is 3 per cent; more salt only makes it saltier, not safer. Dried 梅菜 is salty, and every dish that uses it soaks it first.

The story

The layer under 梅菜扣肉 and the handful in 梅菜蒸肉餅 — the thing families in 惠州 and 石澳 grew and cured themselves. It is the one preserve on this wall that is really farming: a winter of sun and a handful of salt turning three kilos of greens into two hundred grams. It is here because families who have moved buy the sandy packets and do not know that the thing itself is three weeks and a balcony.

Same kind

Garlic and fermented black bean pasteXO sauce, the conpoy and ham chilli relishHouse chilli oil, the noodle-shop jar

Lo Fo Tong is cultural food-heritage reference, not medical advice. If you are pregnant, unwell or on medication, talk to your doctor or registered practitioner before changing what is in the pot.