Wash then finely shred (by hand, or in a food processor) the cabbage and onion.
In a large bowl, combine the vegetables with the salt and spices.
Pound them with a wooden spoon to release all the juices.
Transfer to a steralised 2 litre glass jar, use your fist to firmly pack it down tight as you go. You should be pressing so firm that the brine is released and covers the vegetables.
Leave a one inch gap at the top, as the vegetables will expand as they ferment.
Seal and leave at room temperature for at least three days to get the initial fermentation process started (do not disturb it or open the lid during this time).
After that, the longer you leave it, the better and more mature the flavour - try fermenting for 2 to 3 weeks, tasting at regular intervals.
Store in the fridge once desired taste is reached, and to slow the fermentation process right down