Cut fish into 2cm-thick round slices. Season fish with salt and sprinkle sparingly with tapioca flour. Leave aside. Heat oil in a wok until hot and fry fish for 2 to 3 minutes on each side. Dish out and set aside.
Heat wok with 3 tbsp oil and saute combined ground ingredients until fragrant. Pour in thin coconut milk and add dried tamarind skin pieces and egg plants. Bring to a boil. Add in fish slices and thick coconut milk. Mix in seasoning and boil for 3 to 4 minutes. Dish out and serve hot with nasi dagang.