Remove outer leaves from cabbage, saving one or two. Cut cabbage in quarters and remove the core from each quarter. Thinly slice cabbage so that it is shredded. Place into a large bowl.

Sprinkle salt evenly over cabbage. Thoroughly toss the salt into the cabbage and massage it in until the cabbage begins to wilt and starts losing water.

Firmly pack the cabbage into a large jar using your hands or a spoon. Pour in any liquid that has formed. Place the reserved cabbage leave(s) on the top of the shredded cabbage to prevent any from floating up. Place a weight (a small jar or glass container, filled with rocks or other weights if needed) on top to keep the cabbage weighed down into the liquid. Cover jar with a clean cloth, paper towel or coffee filter secured with a rubber band or twine to prevent any dust or bugs from entering. Let the jar sit at room temperature, away from direct sunlight.

For the first 24 hours, press the cabbage down into any liquid every few hours (don't worry about this overnight). After 24 hours has passed, check the level of liquid. If the cabbage is not completely submerged (it likely will not be), dissolve 1 tsp kosher salt into 1 cup water and pour enough in to cover the cabbage.

After the first 24 hours, continue to press the cabbage into the liquid to keep it submerged a couple of times a day. Foam forming on top of the cabbage is normal, and does not need to be skimmed. If any mold forms, remove it, and the top layer of cabbage immediately.

After 3 days has passed, taste the sauerkraut. From this point on, taste it once to twice a day to determine when it is done. "Doneness" will depend on your taste (the longer it sits, the more sour it will become) as well as the temperature of the room. It may take up to 10 days to be fully fermented.

Once you have determined that your sauerkraut is done, remove the weight and outer cabbage leaves and place the lid on the jar and store in the fridge. It can safely be stored in the refrigerator for up to 2 months.