Simmer sauce ingredients except cornflour and ketchup in a saucepan for 30 minutes.
Stir in the cornflour mixture and cook until the sauce is thick and glossy.
Boil the egg noodles in salted water for 4 minutes.
Drain the noodles and cool them under cold running water.
Section the pork into four portions and warm on a griddle pan for 4 minutes per side.
Heat half the oil in a wok and stir-fry noodles until lightly colored.
Transfer noodles to a plate and keep them warm.
Stir-fry mushrooms and sweetcorn in remaining oil for 2 minutes, then add remaining vegetables sequentially.
Incorporate noodles, sauce, coriander, fish sauce, and soy sauce before serving with pork.