Quarter the cabbage, discard the core and shred the cabbage using a mandoline or a sharp knife. Peel and grind carrots. Combine them in a large pot, add sea salt and brown sugar and knead well until the juice is released, for about 5-7 minutes. It'll take less time if you use white cabbage.

Fill a fitting glass jar (I used the 2 quart jar, similar to that one) with the cabbage mixture. Pack it tightly, so that the juice covers the cabbage. The jar should be filled by 2/3.

Put a fitting lid or small plate to pack the cabbage down and 1-2 quart glass bottle with water on top. If you feel like you packed too much of cabbage in your jar, put it on a plate, as the juice will release while fermenting. Keep the jar at a room temperature for 4 more days, poking the cabbage with a back of a wooden spoon once a day to release the gas from the lower layers.

Keep covered and refrigerate for up to 5 weeks. Enjoy!