Prepare broth base: Combine water and kombu in a pot and heat slowly to around 60°C (140°F) to extract umami. Avoid boiling to preserve kombu flavor. Once heated, turn off the heat.
Cook pork mince: Heat neutral oil in a pan over medium heat. Add pork mince, salt, and black pepper. Cook until the pork turns completely white, about a few minutes.
Add aromatics and chilli paste: Add garlic, ginger, and toban djan (chilli bean sauce) to the pork. Cook for about 1 minute to boost flavor.
Add sake: Add sake to the pork mixture to remove pork smell and enhance flavor. Skip if unavailable.
Combine broth and milk: Add the kombu broth and milk to the pork mixture and bring to a gentle boil.
Dissolve miso: Separately dissolve shiro miso in a small amount of broth to prevent clumping, then add to the pot. Avoid boiling after adding miso to preserve its flavor.
Cook ramen noodles: Cook ramen noodles according to packet instructions using plenty of water to avoid stickiness. Drain and keep warm.
Serve: Place cooked noodles in a bowl, ladle the hot miso broth with pork over the noodles. Garnish with half a nori sheet if desired.