step 1
Put the onion in a pan with 1tsp oil and fry gently for 5 minutes or until it starts to soften
step 2
Add the turmeric, garlic, ginger and red chilli and keep cooking for a few minutes until you end up with a rough, fragrant paste
step 3
Add the tomatoes and simmer for 10 minutes, adding a splash of water if you need to
step 4
Stir in the prawns and cook until they turn opaque