Far from the heavy, fowl-smelling sauerkraut, this is a vividly-colored, tangy-fruity cabbage that you can eat on its own, as part of a meze spread, or add it to any of your winter or spring salads.
We love it so much, that we cannot do without it and as Sandor Ellix Katz suggests, start a new batch before you finish the old one (see NOTE).
Adapted from Mediterranean Vegetarian Feasts
Makes about 4 1/2 quarts (4.3 L)
1 medium-small green cabbage and 1 small red cabbage (5 1/2 to 6 pounds / 2.5 to 2.7 kg total)
3 tablespoons sea salt
1/2 cup (50 g) finely chopped seaweed (dulce, wakame, porphyra, or any other kind), soaked in 2 cups lukewarm water for 30 to 45 minutes
2 to 3 stalks celery (optional)
1 tablespoon caraway or coriander seeds (optional)
About 2 1/2 cups (600 ml) water or 1 1/2 cups (360 ml) water and 1 cup (240 ml) brine from a previous batch of fermented cabbage, as needed
Halve the cabbages, cut off the hard stems, and shred the cabbage into 1/4- to 1/3-inch (6- to 8-mm) strands.
Transfer to a large bowl, sprinkle with the salt, add the seaweed, and pour its soaking juice over the cabbage. Start rubbing and tossing the strands, and continue for at least 10 minutes, until they reduce in volume and start to soften. Add the celery branches and spices, if using, toss, and transfer to a 5-quart (4.7-L) cylindrical jar, pressing down hard with your palms. The liquid will almost reach the top of the cabbage; if not, add a little more water. Cover the entire surface of the shredded cabbage with plastic wrap and place a plate on top, almost as large as the jar. On top of the plate, put a large, heavy can or jar—at least 4 pounds (1.8 kg). Leave on the kitchen counter overnight.
The next day you will see tiny bubbles rising from the bottom of the jar as the cabbage ferments. This happens faster if you have used brine from a previous fermentation. Depending on the room temperature, it could take a couple days before you see the first results of the fermentation process. Be sure to check every day, pressing the shredded cabbage down. Gradually the white and red strands will change into a uniform pink color. Make sure that the cabbage is submerged in the brine at all times.
Taste the cabbage after 4 or 5 days to see if you like it. At this point I usually transfer it to smaller jars, pour enough brine over to cover the cabbage completely, then add a bag filled with clean stones as a weight to keep the cabbage covered in brine. I close the lids and store the fermented cabbage in the refrigerator. The cabbage will continue to ferment slowly in the refrigerator, and after 4 to 5 months it may eventually become too sour and pungent. Mine seldom lasts for more than a few weeks.
NOTE: As Sandor Ellix Katz suggests, start a new batch before you finish the old one. I remove the last pieces with a slotted spoon and then pack the jar with freshly shredded cabbage, which I mix with the leftover brine, adding some salted water made by stirring 1 1/2 to 2 teaspoons salt for each 1 cup (240 ml) water. This cabbage will ferment faster—try it on the third day—and it usually develops a more complex flavor.