- Prep the cabbage. Begin by rinsing the cabbage and discarding any wilted outer leaves of the cabbage. 
- Quarter the cabbage by using a sharp knife. Remove the core and then slice the cabbage into thin strips, aiming for approximately ¼ inch in width. It's not essential for the strips to be perfectly uniform. If you prefer you can also use shredded cabbage. 
- Transfer the sliced cabbage into a large bowl and evenly sprinkle sea salt over it. 
- Mash the cabbage. Now, initiate the mashing process. There's no specific technique; the best way is to just use clean hands and massage the cabbage. The objective is to kickstart the release of juices from the cabbage. 
- Continue mashing or kneading for about 5-8 minutes. By the end, you should have a pool of salty cabbage juice in the bottom of your bowl as the salt draws juices from the cabbage. 
- Canning. Take a few handfuls of the mashed cabbage and place them in a glass jar, then compress them thoroughly using a wooden spoon. The goal is to remove as many air bubbles as possible. 
- Repeat this process of packing and mashing in small batches until the jar is nearly full, but leave approximately 1-2-inch headspace at the top. 
- If the cabbage is not fully submerged in its own liquid, prepare a 2% brine solution to fill the remaining space. (Failing to fully cover the cabbage may lead to mold and other issues.) 
- To make a 2% brine: Dissolve 1 tablespoon of fine sea salt in 4 cups of non-chlorinated water. Any unused brine can be stored in a container or a bag. Store the brine-filled container in the fridge. 
- Cover cabbage with the brine, leaving a 2-inch headspace from the top. If the cabbage keeps floating to the surface, you can use a glass weight to hold it down or wedge a piece of the cabbage core on top.  
- Seal the jar tightly using a linen cloth or a similar cover and secure it with a rubber band. 
- How long to ferment sauerkraut. Place the jar in a dark space at room temperature. Keep away from direct sunlight for at least one week. 
- To prevent any potential spills, consider putting a small dish or tray under the jar, as the jars have a tendency to leak. Additionally, it's a good idea to open the lid after a day or so to release any trapped gases. 
- After one week, taste and smell your sauerkraut. If it's tangy enough to your liking, transfer it to the refrigerator for storage. If you desire a stronger tang, allow it to ferment a bit longer. 
- Enjoy it as a side dish, use it in stir fries or make a hearty polish sauerkraut soup.