Remove 1 leaf from the cabbage before shredding, and set aside. Use a mandoline or sharp knife to finely shred the cabbage. Grate or shred 1 cup of carrots.
Combine the cabbage, carrots, and salt in a large bowl and mix well. Let it sit for 5 minutes.
With clean hands, massage the cabbage mixture for 5 minutes. The cabbage will begin to soften and release liquid. After 5 minutes of massaging, your mixture should feel wet, take up less space in the bowl and there should be some liquid in the bottom of the bowl.
Scoop the cabbage and carrots into a clean jar, then pour any remaining liquid in the bowl over the top. Use a tamper (I use the end of my rolling pin) to firmly pack the cabbage into the jar, pushing the liquid up and over the cabbage. Cut the reserved leaf into a circle slightly larger than the jar and place it on top of the cabbage.
If the cabbage isn't fully submerged, add a weight, like a small jar filled with rocks or a food safe bag of water on top and place it on top of the leaf to keep everything submerged.
Cover with a fermentation lid or plastic lid and let it sit for 1 to 4 weeks, until it reaches your desired flavor. Fermentation lids allow the gas to escape, but if you're using a plastic lid, pop it open once per day to allow any built up gas out.
Store your finished sauerkraut in a sealed jar in the fridge and enjoy within 6 months.