Pour a kettleful of boiling water over the noodles and cover for 10 mins. Meanwhile, mix together the prawns and ginger. Heat 1 tsp oil in a large non-stick frying pan and stir-fry the gingery prawns over a high heat for 2 mins until pink. Tip into a bowl. Return the pan to the heat and add another tbsp oil. When hot, pour in the beaten eggs, spreading out to form an even layer. Cook until set, then lift out of the pan, roughly shred with a knife and set aside. Drain the noodles.
Heat the remaining oil in the pan and stir-fry the beansprouts, bok choi and spring onions for 2 mins or until the bok choi softens. Return the prawns, noodles, eggs and soy sauce to the pan, tossing to combine. Serve immediately with sweet chilli sauce and prawn crackers, if you like.