1. Wash fish and remove any bones.
2. Mince fish and prawns, then transfer to a large bowl.
3. Stir in 60 g (2 oz/1 cup) breadcrumbs, 1 egg, coriander and lemon juice and season with salt and pepper.
4. Mix well and form into 24 balls.
5. Roll balls in remaining egg, then in remaining breadcrumbs to coat completely.
6. chilli for 30 minutes. Meanwhile, heat 2 tbsp oil in a heavy-based pan, add onion and cook, stirring, for 5 minutes until soft.
7. Add chillies, garlic and turmeric and fry for 2 minutes more.
8. Stir in coconut milk and tomatoes and cook, uncovered, for 20 minutes, stirring occasionally, until thickened.
9. Half-fill a deep-fat pan or fryer with oil and heat to 190C (375F) or until a cube of day-old bread browns in 40 seconds.
10. Fry fish balls for 3-5 minutes, until golden.
11. Drain well and serve with the sauce.

Serves 4.