Prepare the Cabbage: Cut the napa cabbage into quarters and remove the core. Cut each quarter into bite-sized pieces. Place the cabbage pieces in a large mixing bowl.

Salt the Cabbage: Sprinkle the sea salt over the cabbage and toss to coat evenly. Let it sit for 2 hours, tossing occasionally. The salt will draw out moisture from the cabbage.

Rinse and Drain: Rinse the cabbage thoroughly under cold water to remove excess salt. Drain well and set aside.

Make the Kimchi Paste: In a separate bowl, combine the sugar, fish sauce, Korean red chili pepper flakes, minced garlic, and minced ginger. Mix well to form a paste.

Combine Vegetables and Paste: Add the chopped green onions, julienned carrot, and julienned radish to the bowl with the drained cabbage. Add the kimchi paste and mix everything together, ensuring the vegetables are evenly coated.

Pack the Kimchi: Pack the kimchi mixture tightly into a glass jar or fermentation container. Press down firmly to remove air pockets and leave some space at the top for expansion.

Ferment: Cover the jar loosely with a lid or cloth and let it ferment at room temperature for 3-7 days. Taste the kimchi daily until it reaches your desired level of fermentation. Once fermented, store the kimchi in the refrigerator to slow down the fermentation process.

Serve: Enjoy your homemade kimchi as a side dish, topping, or ingredient in various recipes.