Sanitize the equipment.
Shred the cabbage using a knife, mandolin, or the slicing function (not shredding function) on a food processor. If the slices are too small or short, they may float above the brine and become exposed to oxygen as they ferment, which can rot.
Place the shredded cabbage in a large, wide bowl. Sprinkle salt all over the cabbage. Use your hands to massage and squeeze the salt into the cabbage until the cabbage releases liquid, about 5 minutes.
Transfer the cabbage and brine to a 1/2 gallon or 2 liter jar. A canning funnel is useful. Tamp down down to submerge the cabbage under the brine and force out any air pockets. Continue until the jar is almost full, leaving 2 inches at the top.
Take the two whole cabbage leaves, rinse, and use them to blanket the shredded cabbage. They should cover all of shredded cabbage below.
If using a fermentation jar, place the fermentation weights on top of the whole cabbage leaves and seal the jar with a fermentation lid.
If you are not using a fermentation jar, fill a smaller, narrow jar with something heavy and place it inside a large ziplock bag. Place the bagged small jar on top of the cabbage to weigh it down and semi-seal the jar. Make sure the weight keeps the cabbage submerged below the brine or it may rot.
Place the jar on top of plate or pie plate to catch any potential liquid displaced during fermentation.
Ferment in a cool place 2-3 weeks away from direct sunlight. Taste after 2 weeks and continue to ferment another week if you would like it more sour.
Transfer the sauerkraut to another jar with a regular lid and store in the fridge for up to 10 months.