Prepare the prawns: If your prawns are frozen, ensure they are fully defrosted and pat them dry with a paper towel. Set aside.
Cook the aromatics: Heat the some low calorie cooking spray in a large pan over medium heat. Add the chopped onion and cook for 5 minutes until softened. Stir in the minced garlic, grated ginger, and red chilli (if using), and cook for another 2 minutes until fragrant. (Add a splash of water if the mixture sticks)
Add the spices: Add a splash of water. Sprinkle in the curry powder, ground cumin, ground coriander, and turmeric. Cook the spices for 1-2 minutes, stirring constantly, to release their flavours.
Create the sauce: Pour in the chopped tomatoes and tomato purée, stirring to combine with the spices and aromatics. Let the mixture simmer for 5 minutes, allowing the flavours to meld.
Add the coconut milk: Slowly pour in the light coconut milk, stirring until the sauce is smooth and well combined. Bring the curry to a gentle simmer and cook for another 5 minutes to thicken slightly.
Cook the prawns: Add the prawns to the sauce, stirring to coat them evenly. Cook for 3-5 minutes, or until the prawns turn pink and are cooked through. Be careful not to overcook them, as they can become tough.
Finish the curry: Squeeze the lime juice into the curry and season with salt and black pepper to taste. Give the curry a final stir.