Slice the red cabbage into very thin strips.
Massage the cabbage with a generous amount of sea salt until it releases a lot of moisture and becomes soggy.
Pack the salted cabbage tightly into a jar, pressing down firmly to remove any air pockets.
Place a weight, like a water-filled bag, on top of the cabbage to keep it submerged and free from air.
Cover the jar and allow it to ferment at room temperature for 2 to 4 days, depending on how warm your kitchen is, until the cabbage takes on a brighter color.
Taste the fermented cabbage and enjoy it on its own, in salads, or as a side with protein.
