In a large wok, add half the oil and fry the garlic, chilli and ginger until golden, about 2 mins. Add the remaining oil, onion, pepper, spring onions, prawns and noodles and stir-fry for a few mins. Push everything to one side, add the egg and scramble. Add the soy sauce mixture, toss again for a few more mins, then remove from the heat. Sprinkle over the coriander leaves before serving.