Thai curry noodle soup

Name: Thai curry noodle soup
Ingredients: 1 tsp vegetable oil; 1 heaped tbsp Thai green curry paste; 220g stir-fry vegetable mix; 150g raw prawns, shelled; 180ml light coconut milk; 220ml vegetable stock, made with 1 low-salt stock cube; 250g straight-to-wok udon noodles; 5g coriander, roughly chopped; 5g Thai basil, roughly torn; 1 red chilli, sliced, to serve (optional); 1 spring onion, sliced, to serve