PREP THE CABBAGE: Remove and discard the outer and damaged leaves. Cut out the core and rinse the cabbage thoroughly, letting water flow between the leaves. Drain well. Reserve one good outer leaf for later.
SHRED THE CABBAGE: Thinly shred the remaining cabbage using a knife or food processor and place it in a large bowl.
ADD SALT: Weigh the shredded cabbage and calculate 2% of its weight to determine the salt needed. Sprinkle the salt over the cabbage and toss to combine. Let the cabbage sit for 1 to 8 hours, then massage it with your hands for about 5 minutes until it releases plenty of liquid.
MIX IN OTHER INGREDIENTS: Add the grated ginger, grated turmeric, caraway seeds, and (if using) cumin seeds. Mix well.
PACK THE JAR: Firmly pack the cabbage mixture into a very clean glass quart jar, pressing it down so the liquid covers the cabbage. Pour any released liquid on top. Cut a circle from the reserved outer leaf to fit the jar’s opening and place it on top. Add a weight to keep the cabbage submerged. If the brine doesn’t fully cover the cabbage and weight, top off with a 2% saltwater solution (1 teaspoon salt per cup water).
FERMENT: Screw on a plastic lid and place the jar in a rimmed pan (to catch any overflow). Let it ferment at room temperature for 1 to 4 weeks, or until it reaches your desired taste.
STORE: Once fermented, transfer the sauerkraut to the refrigerator. Enjoy!