If you are using fresh noodles, blanch them first for 3-5 minutes in boiling water. If you are using dried noodles, cook them in boiling water according to packet instructions.
Plunge them in cold water, drain thoroughly, toss them in the sesame oil and set aside until you are ready to use them. Covered with cling film, they can be kept for up to 2 hours in the refrigerator.
Heat a wok or large frying pan until hot. Add the groundnut oil and, when it is very hot, add the garlic, ginger and spring onions. Stir fry for 15 seconds, then add the pork. Stir well to break up and stir fry for 2 minutes or more until the pork loses its pink colour.
Add the rest of the ingredients except the spring onion garnish, stirring all the time. Bring to the boil, turn the heat down low and simmer for 5 minutes.
Plunge the noodles into boiling water for 30 seconds or until they are just heated through, then drain well in a colander or sieve. Quickly tip the noodles into a large bowl and pour the hot sauce over the top. Mix everything together loosely then sprinkle on the spring onions and serve.