heat the oil in a wok and fry the pork for 10-15 minutes until golden brown.
at the same time blanch the Pak Choi in a pan of simmering water for 4-6 minutes until the stems are tender, drain. In another pan cook the noodles for 2 to 3 minutes, then drain and rinse under cold water.
heat the sesame oil in a frying pan and toss in the greens for a few minutes until they start to colour, add the chilli flakes, half the garlic and toss until they smell aromatic. Remove from heat and keep warm.
Add the spring onions, remaining garlic, ginger and pork and fry for 1Minute. add soy, mirin, rice vinegar and boil for 1 minute.
Tip the noodles into the pork mixture, toss everything together until everything has warmed through. serve in bowls with the chilli greens alongside.