Make sure to sterilize your glass jar and work with clean hands and equipment.
Slice the cabbage into quarters then, thinly slice the cabbage into very thin ribbons or use a mandolin to speed up the process.
Place the thinly sliced cabbage in a large bowl and sprinkle with salt. Knead and press for about 10 minutes until the cabbage becomes soft and the natural brine is coming out from the cabbage. This will help the fiber to break down.
Now pack the cabbage into the jar pressing down each layer. Cover with a whole cabbage leaf and press down the edges making sure it is completely submerged in the brine.
Weigh it down using a small jar that fits inside the lid. You can also use large vegetable pieces or boiled stones.
Place in a dark environment or cover with a cloth and store at room temperature. Make sure the temperature is fairly stable ideally around 20°c. The fermentation will begin within a day and take 2-5 weeks depending on temperature and desired flavor and texture.