Why sauerkraut is so salty, quoted from Rick and sauerkrautrecipes.com:
“I’ve never made sauerkraut in jars, only in crocks so I’m not an expert on this. But when it’s made in crocks you don’t add water. The salt will pull enough water out of the cabbage so that it can be pushed down under the resulting brine. And you don’t cover the crock air-tight at any time. I cover mine with a clean dish towel, allowing it to ferment exposed to the air.”
Added by me: According to sauerkraut recipes, you just need cabbage and salt. The available yeast will ferment the cabbage. Interestingly simple yet heavily salt laden.