Sauerkraut

Pull two or three clean outer leaves off the cabbage and set them aside whole. They go on top at the end as a cap.

Quarter the cabbage, cut out the hard core and shred the leaves 2-3mm thick with a long knife or a mandolin.

Shred it fine and shred it evenly. Thick shreds give up their water slowly and unevenly, and a batch that never makes enough brine of its own is a batch that grows mould.

Put the shredded cabbage and the grated carrot in a very large bowl and weigh them together.

Weigh out salt at 2 per cent of that combined weight, which is the 44g given here for 2.2kg of vegetables.

Weigh the salt rather than measuring it by spoon. Below about 1.5 per cent, spoilage organisms outrun the lactic bacteria; above about 3 per cent the ferment stalls and you are left with salty raw cabbage that never sours.

Scatter the salt over and turn everything through with your hands.

Squeeze the cabbage hard in handfuls for 5-10 minutes, working right through the bowl.

Stop when it has slackened, dropped to about half its volume and a pool of liquid runs out when you press down on it.

Add no water at this stage. The salt is drawing the cabbage's own water out by osmosis, and that liquid is the brine the whole method depends on; anything poured in dilutes it.

Mix in the caraway seeds, peppercorns and bay leaves.

Pack the cabbage into a clean 2 litre jar or crock a fistful at a time.

Press each fistful down hard with your knuckles or the end of a wooden spoon, until liquid rises up over it, before adding the next.

Press the surface down firmly once it is all in, and check that the brine covers it by at least a centimetre.

Leave it half an hour and press again if the brine is short, since the cabbage goes on giving up water as it stands.

Top up with the 2 per cent brine only if it still will not cover after that.

Lay the reserved whole leaves over the surface and tuck them down the sides, then set a weight on top: a small jar of water or a sealed bag of brine.

Every shred must stay under the liquid. This is the whole safety of the method. Submerged cabbage ferments without air and the lactic acid preserves it, while anything standing above the brine grows mould, and mould is what ends most failed batches.

Cover the jar loosely or fit an airlock, and never seal it tight. Fermentation makes carbon dioxide, and a sealed jar builds pressure.

Stand the jar on a tray, out of direct sunlight, in a cool room at 18-20C/64-68F.

Expect bubbles rising through the brine from the second or third day and a clean sour smell within the week.

Skim off any flat white film that forms on the surface with a clean spoon. That is kahm yeast, and it is harmless.

Throw the whole batch out if you find fuzzy growth in blue, green, black or pink. That is mould, its threads run further down than you can see, and it is not worth the risk.

Start tasting from day 7 with a clean fork. It is ready when it tastes sourly of cabbage rather than of salt, has gone pale and slightly translucent, and still crunches.

Reckon on about a week at 20C/68F. A cold room takes three or four weeks and gives a rounder, less sharp result.

Transfer it to a clean jar once it tastes right, press it back under its brine, seal it and refrigerate. Fermentation slows almost to a stop below 5C/41F.

Keep it in the fridge for several months, accepting that it goes on souring slowly and softens over time.

Keep the brine when you drain it, since it seasons soups and salads on its own.

Do not rinse it before eating unless it is genuinely too sour to use. Rinsing washes off the lactic acid that is the entire point of it.

Use it raw in the vinegret in this collection, or stewed long and slow in its own pan for shchi, where it needs three quarters of an hour to soften before it meets the broth.