Thoroughly wash your Napa cabbage. Wash every single piece, discarding any bad or flimsy pieces. Chop whole cabbage leaf into square pieces and place into a large tub or bowl. Once all the cabbage is clean and chopped, get ready to brine the cabbage.
Using a very large tub or container, lay down a layer of cabbage. Sprinkle on some coarse sea salt. You are going to salt every layer; lay down cabbage, sprinkle on some coarse sea salt and repeat. You will use about a 1/2 to 1 cup of coarse sea salt during this process, maybe less.
Pour in 3 cups of cold water, press down on the cabbage and let sit for 2 hours. (You only need 3 cups of water, the cabbage should not be covered in water.) Feel free to cover with plastic wrap if desired. After 2 to 3 hours, mix your cabbage and let sit for another 2 hours, or overnight (at room temperature). If letting sit over night, check the cabbage before you go to bed and add in more cold water. You are doing this so the cabbage doesn't get too salty.
While the cabbage is sitting in the brine, using a food processor, blend/puree together the garlic, ginger, onion, radish, apple and pears. Blend until completely smooth. If needed, you can blend in groups; if your food processor isn't large enough to fit everything. Taste and adjust ingredients as needed, or to your taste.
Remove from the food processor and into a large bowl. Pour in the the fish sauce and the 2 cups of Korean hot pepper flakes (gochugaru) and mix together by hand (using a rubber spatula) until completely combined and somewhat smooth. Set aside.
When the cabbage is ready, rinse and wash the cabbage at least three times, running it under cold water. Place into to a clean container. Using your hands, mix together the cabbage, gochugaru sauce mixture and green onions.
Taste and adjust ingredients as needed. You can add a touch more fish sauce or salt if needed. Mix together and taste one more time. Place into a jar/s or container. To get the leftover gochugaru paste mixture that will be left at the bottom of your tub, add a ½ cup of water to the kimchi tub and a pinch of salt and pour over your kimchi into each jar. Close each jar with lid and leave kimchi out overnight. You can continue to let it sit for a few days to ferment. Enjoy!
This recipe yields about 4 quarts of kimchi.