Step 1: Prepare Your Cabbage. Remove any bruised or discolored outer leaves from the cabbage. Reserve one or two large, healthy outer leaves. Cut the cabbage into quarters and carefully remove the tough core. Using a sharp knife or a mandoline, finely shred the cabbage into thin strips (about 1/8 to 1/4 inch thick).
Step 2: Salt the Cabbage. Place the shredded cabbage in a very large mixing bowl. Sprinkle the non-iodized salt evenly over the cabbage. If using caraway seeds or other spices, add them now.
Step 3: Massage the Cabbage. With clean hands, vigorously massage and squeeze the cabbage for 10-15 minutes. The cabbage will begin to soften and release its liquid, forming a brine. Continue massaging until a significant amount of brine has collected at the bottom of the bowl.
Step 4: Pack the Jars. Tightly pack the massaged cabbage and all its accumulated brine into clean, sterilized wide-mouth glass jars. Press down firmly with your fist or a blunt instrument to remove any air pockets. Ensure the cabbage is packed as densely as possible and leave 1-2 inches of headspace from the top of the jar.
Step 5: Submerge and Seal. Place one of the reserved outer cabbage leaves over the shredded cabbage in each jar, pressing it down to keep the shredded pieces submerged under the brine. If the brine doesn't fully cover the cabbage, prepare a supplemental brine by dissolving 1 teaspoon of non-iodized salt in 1 cup of filtered water and add enough to cover the cabbage. Place a fermentation weight on top of the outer leaf (if using). Secure the jars with an airlock lid or a standard lid (if using a standard lid, 'burp' the jars daily by briefly opening to release gas).
Step 6: Ferment! Place the jars in a cool, dark place, ideally between 60-70°F (15-21°C). Fermentation typically takes 2 to 4 weeks, but can go longer for a tangier flavor. You will see bubbles and cloudiness – these are normal signs of healthy fermentation. Taste after 2 weeks; if it's tangy enough, it's ready. If not, continue fermenting and tasting periodically.
Step 7: Store. Once the sauerkraut has reached your desired taste, remove any weights or airlocks. Seal the jars tightly with regular lids and transfer them to the refrigerator. The cold temperature will significantly slow down the fermentation process. Your homemade sauerkraut will last for several months in the fridge.