Mash brown bean sauce with the back of a spoon and mix well with hoisin sauce, stock and sugar.
Heat oil in a hot wok and fry the spring onion and garlic for 20 seconds. Add pork and stir fry until it separates into small pieces and is coloured, about 2 to 3 minutes. Add the bean mixture, reduce heat and simmer for 5 minutes.
Cook noodles in boiling water for 4 to 5 minutes. Dra