Cabbage is shredded and packed in quart jars with one tablespoon of salt per jar. Other optional ingredients like carrots and juniper berries can be added, too. The cabbage is bruised to release liquid by pounding and pressing with a wooden pestle.
The jars are covered with lids, but not too tightly, so that the carbon dioxide gas given off by the lactobacillus bacteria can escape. After a few days to a week of vigorous fermentation, the lids can be tightened. It is best that the jars be kept in a tub or other container that does not react with salt during this phase, as some brine will escape.
The salt and exclusion of air provide an an environment that favors the lactobacillus bacteria. The bacteria consume sugar and give off lactic acid which pickles the cabbage.
Lactic acid fermentation is very trendy, and very traditional. Sauerkraut has long been recognized as a winter source of vitamin C, and more recently is getting recognition for being a probiotic, providing organisms that are beneficial to our guts.
Sauerkraut is German for "sour cabbage". During WWI, sauerkraut was dubbed "Liberty Cabbage", and during WWII, "Victory Cabbage" when Germany and things German were not in favor.