Cook the noodles following the pack instructions, drain and set aside for later. Heat the oil in a large frying pan and pour in the beaten egg. Swirl around the pan to make a thin omelette, cook for 1-2 mins, then flip over and cook the other side for 1 min. Tip out and slice into thin strips.
Add the chilli and ginger to the pan, fry for 1-2 mins then tip in the noodles, prawns and egg. Splash in the soy sauce and stir-fry for 1 min more. Throw in the chopped herbs and pour over the lime juice and zest, then sprinkle over the chopped peanuts and serve.