SOAK PORK NECK BONES: Add pork neck bones to a large bowl. Cover with cold water and soak for 30-60 minutes. (You can keep on the kitchen counter unless it's very warm in your kitchen, in which you should store in the fridge.) This removes all the blood to make a clearer, better tasting broth.
Drain and rinse in cold water. Transfer to a large stock pot.
PARBOIL PORK NECK BONES: Add pork neck bones to a large stock pot. Cover with cold water and bring to a boil. There will be a lot of scum and fat particles that rise to the surface. Boil furiously for 5 minutes.
DRAIN AND CLEAN PORK NECK BONES: drain pork neck bones in a colander and rinse the bones under running cold water. Make sure to rub off all the grime and fat particles that stick to the pork bones; use your hands to rub the bones and flesh under cold running water. Also, wash the pot in order to remove the scum and bits stuck to the side.
MAKE BROTH: Add clean, parboiled pork bones to the clean stock pot. Add onion, ginger slices, and bay leaves. Add enough water to cover, about 6 cups. Bring to a boil then lower heat. Simmer, covered, until the meat is soft and falling off the bone, about 45-60 minutes.
Add potato, carrots, and kimchi. When the pork is tender and falling off the bone (poke with a chopstick to see if it goes through easily), add the potatoes, carrots, and kimchi. Cover and cook until soft and cooked through, about 10-15 minutes more.
MAKE SPICY PASTE: While the potatoes and carrots cook, make the spicy paste. In a medium bowl, add ingredients for spicy paste and mix well. Add immediately to the simmering pot, mixing well so there are no big chunks. Simmer until all the flavours come together, about 5-10 minutes more.
GARNISH: Add a few grinds of black pepper, a drizzle of perilla seed oil, and a generous sprinkling of finely sliced perilla leaves and green onions. Serve bubbling hot with rice, kimchi, and banchan (side dishes) of choice. Enjoy!