Remove outer leaves of each cabbage head
Chop cabbage into smaller chunks, removing the core. Shred in food processor.
Add all shredded cabbage to a large bowl, and add sea salt.
Massage cabbage until brine forms. When you can squeeze the cabbage and it's dripping with brine, it's ready.
Add all cabbage to a 1/2 gallon mason jar. Top off with remaining brine.
Place excess cabbage leaves in the jar to keep the shredded cabbage below the brine line. Top with a weight.
Place a lid loosely on the jar, and store on countertop (room temperature) until sauerkraut is to your liking.