Cut 1 medium head of Napa cabbage lengthwise through the stem into quarters. Cut the cores from each piece. Cut each quarter crosswise into 2-inch-wide strips.
2 lbs Napa cabbage
Place the cabbage in a large bowl and sprinkle with 1/4 cup iodine-free sea salt or kosher salt. Using your hands, massage the salt into the cabbage until it starts to soften. Add enough water to cover the cabbage. Put a plate on top of the cabbage and weigh it down with something heavy, like a jar or can of beans. Let it stand for 1 to 2 hours.
1/4 cup Salt
Rinse the cabbage under cold water 3 times. Set aside to drain in a colander for 15 to 20 minutes.
Rinse and dry the bowl used for salting. Add the garlic, ginger, sugar, and fish sauce and stir into a smooth paste.
6 cloves Garlic, minced, 1 inch Fresh ginger, minced, 1 tsp Sugar, 2 Tbsp Fish sauce
Stir in the red pepper flakes; set aside until the cabbage is ready.
4 Tbsp Red pepper flakes
Gently squeeze any remaining water from the cabbage and add it to the spice paste. Add the radish and scallions.
8 oz Daikon radish, peeled and cut into matchsticks, 4 ea Scallions, cut into 1" pieces
Using your hands, gently work the paste into the vegetables until they are thoroughly coated. The gloves are optional here but highly recommended to protect your hands from stings, stains, and smells!
Pack the kimchi into a 1-quart jar. Press down on the kimchi until the brine (the liquid that comes out) rises to cover the vegetables, leaving at least 1 inch of space at the top. Seal the jar.
Place a bowl or plate under the jar to help catch any overflow. Let the jar stand at cool room temperature, out of direct sunlight, for 1 to 5 days. You may see bubbles inside the jar, and brine may seep out of the lid.
Check the kimchi once a day by opening the jar and pressing down on the vegetables with a clean finger or spoon to keep them submerged in the brine. (This also releases gases produced during fermentation.) Taste a little at this point, too! When the kimchi tastes ripe enough for your liking, transfer the jar to the refrigerator. You may eat it right away, but it's best after another week or two.