Weigh your cabbages to get an exact weight in grams (2kg=2000 grams). Multiply the total weight by 2% to get the minimal salt in grams, and 3% for the upper range of salt in grams. For 2000 grams of cabbage (4.4 lbs) this will equal 40-60 grams but will vary greatly based on the actual weight of your cabbages.

Use the upper range of salt if your cabbages are dry or you are a beginner. Use the lower range if you are using a starter culture and are comfortable with fermentation.

Remove the outer leaves of your cabbage(s) and cut them in half. Then use a sharp knife to remove the core from the middle and discard it.

Slice the cabbage halves into thin slices, anywhere from ⅛ - ¼" thick. You could also use a food processor or box grater to shred the cabbage, but in my opinion, this style of sauerkraut ferments too quickly and has a less crisp texture.

Add the cabbage shreds to a very large bowl (or several bowls) and sprinkle the required amount of salt all over the surface.

Use your hands to gently massage the salt into all of the shredded cabbage leaves. Then, use a kraut pounder to begin to "bruise" the cabbage, helping to release some juices.

Once the salt has thoroughly been worked into the cabbage, cover with a lid or damp tea towel and allow to rest for at least 30 minutes and up to 1 hour. This will give the salt a chance to work and pull any liquid from the shredded purple cabbage.

After the cabbage has rested check to see the amount of liquid that was produced - if it was a mere few tablespoons, you're going to need to add water or brine to get an adequate amount of liquid.

Pack the cabbage into your jars (including the brine), using a kraut pounder or the bottom of a wooden spoon to pack it in super tightly. As you press, you should see some liquid rise up to cover the cabbage.

If you're using a starter culture (like leftover sauerkraut brine, kombucha, water kefir, or whey), add that when you start to reach the mouth of the jar. You'll want to use about 1-2 tablespoons per half gallon jar or 1 ½ teaspoons to 1 tablespoon per quart jar.

If the liquid level is not high enough to submerge the cabbage, either add a small amount of water (if you’re using a 3% salt solution and/or a starter culture), OR prepare a fermentation brine (*See notes).

Pour the water or brine into the jar just enough to submerge the shredded cabbage.

Once you have enough liquid in the jar, add a fermentation weight to the top of the jar or crock and press down. This will hold your cabbage under the brine, bringing the liquid level up. If you don’t have a fermentation weight, check the notes** for an alternative.

Wipe around the edge of the jar to clean up any cabbage pieces or debris, and top with a lid (plastic is preferred).

Place your sauerkraut in a room temperature (around 68ºF or 20ºC) place in your kitchen, in a dark cupboard if possible (though not necessary), and ferment for 2-6 weeks, or until the bubbling and activity have reduced and the red sauerkraut tastes and smells pleasantly sour.

Once your red sauerkraut is fermented to your liking, you're ready to transfer it to storage. If the liquid level is ample, you can remove the fermentation weight. Place a lid on the jar and transfer it to the fridge or cold storage.