Preheat the oven to 150°C. Place a large casserole pan on the hob, add 1 tbsp of the oil and heat until very hot.
Season the pork with the salt and pepper and place in the pan with the hot oil. Sear on all sides.
Mix the vegetable stock with the miso paste and pour over the pork.
Add in the onion, the whole carrot, garlic and ginger.
Now add the mirin, soy sauce and the red chilli. Bring to the boil, then place a lid on the pan and place in the oven for 4 hours.
Remove and discard the layer of fat. Take the pork out and shred the pork using two forks.
Place a sieve over a large bowl and strain the cooking liquid. Throw away the strained vegetables and place the liquid back in the pan with the shredded pork.
Boil the eggs for 6 minutes, then immediately place the eggs in iced water to stop the cooking.
Place the noodles in a pan of boiling water and boil for 5 minutes. Then drain, run under cold water and put to one side.
Add the leek and spring onions to a frying pan with a little oil, season with a pinch of salt and pepper then fry for 5 minutes. Add the bok choi to the pan to wilt.
Divide the noodles between four bowls. Top with the hot broth and shredded pork.
Carefully peel the boiled egg, slice in half and place on top with the fried leeks, spring onions and bok choi.