1Cut the napa cabbage into quarters and remove the core. Chop the quarters into bite-sized pieces.
Dissolve the sea salt in 4 cups of water to create a brine. Submerge the cabbage pieces in the brine and let it sit for 1-2 hours, turning occasionally.
Rinse the cabbage thoroughly under cold water to remove excess salt. Drain well and set aside.
In a large bowl, combine the grated ginger, minced garlic, sugar, soy sauce, and Korean red pepper flakes (gochugaru) to create the kimchi paste.
Add the julienned daikon radish, chopped green onions, and julienned carrot to the bowl with the kimchi paste. Mix well to coat the vegetables evenly.
Add the drained cabbage to the bowl and mix everything together until the cabbage is well coated with the kimchi paste.
Pack the kimchi mixture tightly into a clean, airtight container or jar, pressing down to remove any air bubbles.
Leave the container at room temperature for 1-2 days to ferment. Check daily and press down the kimchi to keep it submerged in its juices.
Once fermented to your liking, transfer the kimchi to the refrigerator. It will continue to develop flavor over time and can be enjoyed for several weeks.