Scale and clean fish, season with salt, dry and fry in very hot oil till golden brown. Drain.
Slice ginger and garlic.
Remove seeds and cut chillies into quarters.
Pound turmeric and fry in four tbsp oil until colour is absorbed into oil. Fry sliced ginger and garlic till golden brown. Add vinegar, salt and sugar to taste. Add red and green chillies and simmer for five more minutes.
Reduce heat further and ease in the fried fish.
Cover kuali and turn off the fire.
Remove cover and let the dish cool before storing.