Halve the cabbage and remove the tough core, then chop into 1-1.5 inch pieces. Rinse in cold water and drain thoroughly — excess water will dilute the brine.
Dissolve 3 Tbsp salt in 3 cups water, stirring until completely clear. Place cabbage in a large bowl, pour the salt water over it, then sprinkle the remaining 1 Tbsp salt directly on top.
Let the cabbage brine for 1 hour, tossing every 20 minutes to ensure even salting. The cabbage will release its water and start to wilt.
⏱ 1 hr
Meanwhile, mince the garlic, onion, red pepper, and ginger as finely as possible. Combine with sugar, chili powder, and fish sauce, stirring into a thick paste. This yangnyum will coat every piece of cabbage.
Chop green onions and chives into 2-inch lengths. Keep them separate from the yangnyum for now — they'll add fresh crunch to the finished kimchi.
Test the cabbage by bending a piece — it should feel flexible, not rigid. Rinse thoroughly under cold water and drain completely. Press gently to remove excess moisture.
Wear gloves and combine the drained cabbage with yangnyum, green onions, and chives. Mix thoroughly, massaging the paste into every piece until evenly coated and bright red.
Taste a piece and adjust — add more fish sauce for saltiness or chili powder for heat. The flavor should be bold since fermentation will mellow it slightly.
Pack tightly into a clean container, pressing down to eliminate air pockets. Ferment at room temperature for 2 days, then refrigerate for several days for deeper flavor development.
⏱ 48 hrs