Sprinkle salt and turmeric over the fish and set aside.
In a frying pan over a medium heat, warm a little oil then add the onion, season to taste then add the diced tomatoes and cook and stir for a minute. Add chilli powder then add the ginger, garlic and green chilli. Cook for 5 to 8 minutes, stirring frequently. Add the passata, vinegar and sugar then cook for 2 minutes. The sauce is ready, so set it aside while you cook the fish.
Preheat the oven to 150 degrees C.
In a frying pan over a medium heat, warm a little oil and fry the fish fillets until they are an even colour throughout. Transfer the fish to a baking dish and pour the tomato sauce over it.
Bake in the preheated oven for 30 minutes. Remove from the oven and transfer to serving plates. Garnish with fresh coriander leaves and serve.
A firm white fish would work well in this recipe such as cod, sea bass or pollock.