Place 1 gallon water and ½ cup salt in a large bowl or container and mix well until salt dissolves.
Cut the head of cabbage in half lengthwise; add it to the salted water and let it soak for 1 hour.
Add the rice flour and 1½ cups water to a small pot or sauté pan and mix well until there are no lumps. Turn the heat to medium; stir well with a rubber spatula or wooden spoon until a thick paste forms. Remove from heat and allow the paste to come to room temperature; add in the fish sauce, chili flakes, garlic, onion, ginger and chives.
Divide the rice flour mixture into 2 portions. Remove the cabbage from the brine; shake well to remove any excess liquid. Place 1 portion of the rice flour mixture in between the leaves of each half of the cabbage.
Place the cabbage halves into a container or zip-top bag and leave at room temperature for 2 hours to start the fermentation process, then refrigerate. The kim chee is ready to eat after 1 week or it can continue to ferment for up to 6 months. It will sour as it gets older.
Chef’s Notes: For a more robust flavor, add raw squid or oysters to the mixture. This also speeds up the fermentation. And, for a sweeter kim chee, add grated carrots, radish or other root vegetables to the mixture.