Heat 1 tsp sesame oil in a wok until very hot. Stir fry the chilli, ginger and garlic until fragrant. Add the spring onions for a few minutes before scraping everything to one side and adding the egg. Quickly stir-fry, and toss everything around in the wok to get scrambled egg mixed with the spring onions and chilli. Toss in the mooli and courgette noodles, and stir-fry for 4 minutes, then add the beansprouts and the prawns. Cook for another 2 minutes until the prawns have warmed though and the water from the veg has evaporated. Add the lime juice and fish sauce. Scatter with the coriander and chopped peanuts to serve.