Sauerkraut is cabbage and salt. That is the entire ingredient list. Everything else is technique, and there is very little of it.
If you have never fermented anything, start here. It is almost impossible to get badly wrong, and the failure mode is obvious rather than dangerous.
What you need
- Green or white cabbage — about 1kg per litre of crock capacity
- Fine sea salt, non-iodised — 2% of the cabbage's weight
- A fermentation crock with weights, or a large jar
- Kitchen scales. Not optional.
For a 3L crock you want roughly 2–3 cabbages. For a 7L, five to seven.
The method
1. Weigh as you go. Remove the outer leaves and set two aside. Quarter the cabbage, cut out the core, and shred it as finely as you have patience for. Weigh the shredded cabbage. Multiply by 0.02. That is your salt.
2. Salt and wait. Toss the shredded cabbage with the salt in a large bowl. Leave it twenty minutes. It will start to slump and release water — this is the brine, and you are not going to add any.
3. Work it. Squeeze and massage handfuls for five to ten minutes. It will go from dry-looking to visibly wet, and the volume will roughly halve. When you grab a fistful and liquid runs freely, stop.
4. Pack it down. Transfer to the crock in handfuls, pressing hard with a tamper or your fist after each. You are driving out air pockets. Keep going until the brine rises above the cabbage.
5. Cover and weight. Lay the reserved whole leaves over the surface, then set the ceramic weights on top. Everything solid must sit below the brine line. Anything above it will spoil.
6. Seal. Fill the water channel around the rim, set the lid in, and leave it somewhere out of direct sun at cool room temperature — 18–20°C is ideal.
What happens next
For the first few days, nothing visible. Then bubbling — gas escaping through the water seal, which will burp audibly. This is the point of a water-lock crock: gas leaves, air never comes back.
Check the water channel every few days and top it up. It evaporates.
At week two, taste it. Push the weights aside with a clean utensil, take a small forkful, replace everything under the brine. It will be sour, still crunchy, and recognisably sauerkraut.
Three to four weeks gives a rounder, deeper sourness. Six weeks gives something quite serious. There is no wrong answer — jar it when it tastes right to you, and refrigerate.
Troubleshooting
White film on the surface. Almost certainly kahm yeast. Harmless, slightly musty. Skim it off and make sure everything is submerged.
Fuzzy mould — blue, green, black. Different story. Something was above the brine. Discard the batch.
Not enough brine. If the cabbage was old and dry, top up with 2% brine — 20g salt per litre of unchlorinated water.
Too salty. It will mellow as it ferments. Give it another week before deciding.
After the first batch
Once plain kraut works, the variables open up. Caraway is traditional. Juniper berries and a bay leaf make it feel alpine. Grated carrot and ginger make something brighter that children will actually eat.
The ratio stays the same. Two percent salt, everything under the brine, patience.