Prep your vegetables: Remove the outer cabbage leaves and set a few large, undamaged ones aside. Thinly slice the cabbage and onion.
Shred the carrots and mince the garlic.
Mix and let it rest: Add all the ingredients into a large bowl. Mix well with your hands or a spoon.
Cover with a clean towel and let it sit for 30 minutes so the salt can draw out the moisture.
Pack into jars: Use a tamper or wooden spoon to firmly pack the slaw into a half-gallon jar (or 2 quart jars). Be sure to press it down until it’s submerged in its own brine.
Weigh it down: Place a cabbage leaf on top of the slaw to help hold little bits down, then add your fermentation weight to keep everything submerged.
Ferment: Cover with a fermentation lid and let the jars sit at room temperature for 2 weeks.
Store: After 2 weeks, transfer the slaw to the fridge or a cool cellar. It’ll keep for several months sealed in an airtight jar.