Place all broth base ingredients except the bonito flakes into the pressure cooker, bring it to a boil.
After boiling, use the mesh strainer to scoop out the foam and fat, rinse it off from the strainer in a bowl of cold water. Repeat process until broth looks clear of foam and fat as much as possible.
Cook high pressure for 25 mins.
Quick release after it's done, remove pork belly and set aside.
Crush the bones using the hand blender.
Add in the dried bonito and boil on low heat for 10 mins.
Strain soup through a colander.
Chashu sauce
Place all chashu sauce ingredients into a small pot and bring it to a boil to evaporate the alcohol.
After it cools down, place pork belly with just enough sauce to cover and leave it in the fridge for a few hours or overnight.
Drain chashu before serving and slice thinly, place them on a oven-safe pan.
Torch the pork slices until browned. Set aside.
Ramen Egg
Place steamer rack or trivet and add 1 cup of cold water in the pressure cooker. Place the eggs at the center of the rack. Pressure Cook at low Pressure 4 minutes + Quick Release.
Open the lid and immediately place the eggs in a bowl of cold water. Pour out the water in the bowl and refill it with cold tap water and place the eggs back into the bowl for another 3 minutes.
Carefully crack and remove the eggs shells.
Dilute the rest of the chashu sauce with equal parts water and place boiled eggs in marinade and leave in the fridge for a few hours or overnight.
Cooking Miso Soup and Assembly of the Ramen
Sauté the garlic and ginger in a big soup pot over low heat.
Add in miso paste and soup broth base that we've made earlier, bring it to a boil over medium heat.
Meanwhile, boil water in another pot and cook ramen noodles. Use your fingers to spread out ramen noodles as much as possible before cooking.
Add ramen noodles into boiling water, wait until water comes to a boil again, then cook accordingly to the package instructions.
DO NOT rinse noodles after cooking, place in bowl for serving.
Add bean sprouts, chinese chives to the boiling soup broth.
Pour soup broth over boiled noodles.
Top with 2 halves of a ramen egg, chashu pieces bean sprouts, chinese chives and leek.