Trout - 1 lb.
Onion - 1/4 of a large one
Slice it thin & long, & cut into halves.
Shallot - 1 big one, cut into small pieces
Ginger - 0.5" piece, cut into thin slices
Green chili - 2, cut into half (long)
Tomato - 1, medium sized
Slice it thin and long, and cut into halves.
Coconut milk - 1/3 of the can (4.5 oz)
Tomato puree - 3 spoon
Mango powder - 1/2 spoon.
Uvula powder - 1 pinch.
Fish masala - 3 spoon
Curry leaves - optional
salt - as needed
oil - 2 spoon
mustard seed - 1/4 spoon

Heat the oil, fry mustard seeds, then add onion and stir for a while.
Then add green chili, ginger and shallot pieces (and curry leaves).

Stir for a few minutes. Add tomato, and then tomato puree; stir well, then add salt, uvula (methi/fenugreek) powder, mango powder and fish masala. (If you don't have Kerala fish masala, then add 1.5 spoon [fine] coriander powder, 1 spoon chili powder,1/5 turmeric powder, one pinch more uvula powder.)

Stir well, then add coconut milk.

When it boils, add the fish pieces; stir slowly, then cover it and cook on low-medium heat.

Stir once a while (careful not to break the fish pieces) until it is cooked.