In a large bowl shred cabbage , add sea salt. Let stand 20 minutes .
Massage cabbage for 5 minutes to release brine. Pack into pint jars, making sure the brine covers the cabbage by 1 inch and there is 1 - 2 inches space above the brine at the top of the jar. Fold and push 1 cabbage leaf into the jar to release the brine.
Close jars and set into a baking pan or other container to prevent spillage. Let stand in a cool dark place for 5 days. Slowly release the air from the jars making sure liquid does not spill out. Reseal immediately and let stand another 5 days. Repeat this procedure another 2 times. 20 days all together.