Clean fish head and remove scales. Rinse and set aside.
Heat oil in pot and fry the mustard seeds until it begins to pop. Add the ground shallots, garlic and ginger. Add fenugreek, curry leaves and cinnamon stick and fry until fragrant.
Mix a little water to the curry powder blend to make a paste. Add to the pot, stir the ingredients together and cook until oil separates.
Slowly pour in the thin coconut milk and bring to a boil. Add brinjals, tamarind juice and fish head. Cook until the fish is almost done.
Add the tomatoes, lady fingers, green chillies and thick coconut milk. Adjust the amount of liquid by adding water. Stir and bring to a boil. Season to taste and cook until oil floats to the top. Garnish with chopped spring onions and fried onions.
To make a healthier version of this curry, use evaporated milk instead of coconut milk.