Heat the oven to 190°F. Mix together all the salsa ingredients. Place in a serving bowl and set aside.
Heat the oil in a wok and stir-fry the chilli, cumin seeds, garlic, onions and peppers over a high heat for 5-6 minutes until softened. Add the courgettes and baby sweetcorn and continue to stir-fry for 4-5 minutes until they are just tender.
Wrap the tortillas in foil and heat them in the oven for 5 minutes.
Add the prawns to the vegetables and stir-fry until they are heated through. Stir in the coriander and season to taste. Pile onto a large serving platter.
To serve, each diner spreads a spoonful of yoghurt over a warm tortilla and tops it with some of the prawn mixture and a spoonful of the salsa. The tortillas are then rolled up and eaten with the fingers, or you can use a knife and fork. Serve with any remaining salsa, garnished with coriander and lime.