1) Put the prawns in a non-metallic bowl and add the chilli dipping sauce and half the lime zest and juice. 2) Combine well and leave to marinate in the fridge for about 30 minutes. 3) Cook the rice noodles according to the pack instructions, cool under cold water and drain well. 4) Add the fish sauce, half the oil and the remaining lime juice and zest. 5) Fold in the coriander, beansprouts and spring onion whilst the noodles are hot. 6) Heat a wok or a large frying pan until searing hot, add the remaining oil. 7) Add the prawns and stir-fry over a medium heat for 3 minutes until cooked through and pink then add the noodle mix to reheat.