Mix turmeric powder, chili powder, salt, rice flour, and water in a bowl. Add the fish and mix to coat well.
Heat oil in a pan and shallow fry the fish until golden brown. Remove onto absorbent paper.
To the same oil (add more if necessary), add onion seeds (or cumin seeds), green chilies, chopped garlic, and onions. Saute until translucent.
Now add cumin powder, turmeric powder, coriander powder, and chili powder. Stir and continue to cook for 2 more minutes.
Now add diced eggplants and cauliflower florets. Cook until the vegetables have softened a little, approximately 3-4 minutes. Add tomato paste and give everything a good stir. Cook over medium heat until the raw tomato and spice smell has dissipated, approximately 8-10 minutes
Add enough coconut milk to immerse everything, adjust salt, and cover and cook over medium heat for 5-6 more minutes or until oil separates.
When the vegetables have cooked all the way, add the fried fish fillets. Stir and sprinkle fresh coriander leaves and turn off the heat immediately (if using fish steaks, let it simmer for another minute). Serve with steamed white rice.