Place the pork neck bones in a large mixing bowl. Fill it with cold water, ensuring all bones are completely submerged. Allow the bones to soak while you prepare the rest of the ingredients.
In a large pot or Dutch oven, fill it up about 2/3 of the way with water and heat over medium-high heat. Bring to a boil then blanch the napa cabbage for 2 minutes. Transfer to a bowl or large strainer and rinse under cold water.
Once cooled completely, rip the napa cabbage into strips lengthwise. Squeeze the excess water out then transfer it to a medium-sized mixing bowl. To the bowl, add 1 tablespoon of doenjang and sesame oil. Using your hands, rub the seasonings into the cabbage until evenly coated. Set aside for later.
Drain the pork bones and rinse them under cold water. Place the pork bones into the same pot used to blanch the cabbage. Boil for 5 minutes then strain. With the cold water running, rinse and clean the pork bones thoroughly to remove any excess fat or scum in between the bones.
To a clean pot or Dutch oven, add 12 cups of water, the cleaned pork bones, garlic cloves, ginger, onion, scallion (white parts only), daepa (white parts only), red pepper, 1 1/2 tablespoons doenjang, and mirin. Cover the pot with a lid and simmer over medium heat for 90 minutes.
In the meantime, prepare the sauce by combining gochujang, gochugaru, soup soy sauce, fish sauce, perilla seed powder, and 2 tablespoons of water. Mix until well combined then set aside.
After 90 minutes, add the seasoned napa cabbage, daepa (green parts only), potatoes, and sauce. Cover with a lid and simmer on medium heat for 30 minutes.
Add the perilla leaves and scallions (green parts only), then simmer for 10 minutes.
Serve immediately and enjoy!
