Rub the fish pieces with turmeric powder and a little salt, then let them marinate.

Heat the coconut oil in a clay pot and add the mustard seeds and curry leaves, letting them sputter until fragrant.

Add the sliced onions and sauté, stirring frequently, until soft and translucent.

Add the julienned ginger, sliced garlic, and slit green chilies, and cook, stirring constantly, until the raw smell disappears.

Add the black pepper powder and stir briefly until it becomes fragrant.

Pour in the thin coconut milk extract and the water, and bring the curry to a gentle simmer.

Slide the marinated fish pieces into the simmering curry and poach gently without stirring vigorously.

Pour in the thick coconut milk extract and warm the curry through gently, without letting it boil.

Turn off the heat and let the curry rest so the flavors settle.

Ladle the fish moilee into a bowl and serve hot with steamed rice or appam.