1 head red cabbage, shredded
1/2 apple, seeded
Kombu seaweed, soaked, as needed
Outer cabbage leaves, as needed
Place half of the shredded cabbage in a ceramic or glass container. Press down firmly. Place the apple in the center of the cabbage. Place the remaining 1/2 of the shredded cabbage on top, always pressing it down firmly. Cover the top of the cabbage with a layer of hydrated kombu seaweed. On top of the kombu, place a layer of cabbage leaves. Place a heavy weight on top of the cabbage leaves, making sure that the entire container is covered so that no foreign matter can enter the kraut.
The cabbage will begin to foam and bubble as a result of the fermentation process. Leave out at room temperature. After 3-5 days (when ready), discard the cabbage leaves, kombu and apple from in the middle. Place the sauerkraut in a container for storage and refrigerate.