Place the thinly sliced cabbage in a large mixing bowl along with coarse sea salt. Use your hands to massage the salt into the cabbage and squeeze it in batches for a few minutes. This process will release the water within the cabbage, which ends up being the liquid in which the cabbage ferments.
Transfer the salty squeezed cabbage to the fermentation crock (make sure all of the salt gets in there, too!) and place the ceramic weight on top of it.
Let the crock sit, preferably in a warm, dark place like a closet or pantry. After 24 hours, check the status of the cabbage. If it isn’t fully submerged in its own liquid, dissolve a couple tablespoons of sea salt in spring or well water and add it to the crock so that the cabbage is fully covered in water.
Allow the crock to sit for a full week, checking on it periodically to be sure it isn’t moldy. After a few days, it will begin to smell vinegary and after a week, you’ll have sauerkraut!
Transfer the sauerkraut (along with the liquid) to a sanitized seal-able jar and refrigerate. When sealed properly, sauerkraut should last in your refrigerator for months on end.