01 - Remove any damaged outer leaves from the cabbage. Cut into quarters, cut out the tough core, and thinly slice the quarters into fine shreds using a sharp knife or mandoline.
02 - Place the shredded cabbage in a large mixing bowl and sprinkle evenly with the sea salt. Using clean hands, massage the salt into the cabbage vigorously for 5 to 10 minutes until the leaves soften and release a generous amount of liquid.
03 - If desired, fold in caraway seeds, grated carrot, or thinly sliced apple and toss until evenly distributed throughout the cabbage mixture.
04 - Transfer the cabbage and all its collected juices into a sterilized fermentation crock or a large glass jar with at least 2-liter capacity. Press the cabbage down firmly using your fists or a fermentation tamper, ensuring the cabbage is completely submerged beneath its own brine.
05 - Place a fermentation weight or a clean smaller jar filled with water on top of the cabbage to keep it fully submerged. Cover the vessel with a breathable cloth or a fermentation lid that allows gases to escape while keeping debris out.
06 - Store the jar at room temperature (65–72°F) in a location away from direct sunlight. Allow the cabbage to ferment for 7 to 21 days, beginning to taste after the first week. Once the desired level of tanginess is reached, transfer to the refrigerator to halt further fermentation.
07 - Serve chilled or at room temperature as a side dish or condiment alongside sausages, roasted pork, or hearty potatoes.