1. Chop the Napa cabbage into bite-sized pieces and place in a large mixing bowl.
2. Sprinkle the salt over the cabbage and massage it in. Let it sit for 1-2 hours until it wilts.
3. Rinse the cabbage under cold water to remove excess salt and drain well.
4. In a separate bowl, combine the daikon radish, carrot, garlic, ginger, gochugaru, fish sauce, and green onions.
5. Add the cabbage to the mixture and toss to coat evenly.
6. Pack the mixture tightly into a fermentation jar, pressing down to remove air bubbles.
7. Seal the jar and let it ferment at room temperature for 1-5 days, checking daily and pressing down if needed.
8. Once fermented to your liking, store the kimchi in the refrigerator.