Mix together the vinegar, sugar, fish sauce and soy sauce in a bowl.
Soak the noodles in boiling water according to the pack instructions.
Heat the oil in a frying pan while the noodles are soaking, add the chilli, red pepper and mangetout and fry for 4–5 minutes until softened.
Drain the noodles and add to the pan with the vinegar mixture. Toss together and serve immediately.