Peel and discard some of the outer cabbage leaves, saving two clean and unblemished leaves to place on top of your ferment later. Rinse and pat dry the cabbage. Quarter and remove the core. Sliced each cabbage quarter into thin ribbons.
Once all cabbage is prepared, place in a very large bowl and sprinkle with salt. With freshly washed and very clean hands start tossing, squeezing, and smashing. Continue these motions for approximately 30 mintues until a substantial about of liquid accumulates in the bottom of the bowl and the cabbage is wilted. Mix in fennel and caraway seeds.
Back into a one-gallon jar or fermentation crock. Press firmly to release more liquid in order to cover the cabbage. Place optional grape leaves on top of the cabbage at this time if desired. If there is not enough brine produced naturally, you may add some of the optional brine indicated above to cover. Place the reserved cabbage leaves on top of the soon to be kraut. Weigh down with fermentation weights like these OR by placing a gallon size freezer bag filled with the optional brine on top of the cabbage leaves. If using a jar, place on a lid with an airlock, or if using a crock follow instructions from the manufacturer. If no instructions exist for your crock, place a clean cloth or lid over crock to prevent bugs and contamination (if no airlock for your jar lid, place lid on somewhat loosely to release pressure from ferment. You should see signs of fermentation such as bubbling within a few days. Allow your cabbage to ferment for 3-4-5 weeks, although it may be down sooner depending on the heat in your home. Start tasting the sauerkraut after about a week of active ferment with a clean utensil. The ferment is "done" when you are happy with the flavor.
Pack finished sauerkraut with brine into clean jars and refrigerate. The cool temperatures will slow the fermentation significantly, making this sauerkraut relatively stable under cold refrigerator conditions. Some krauts last in excess of a year if properly chilled. Discard if off odors, slimy textures, or mold occur.