Mix everything in a bowl, except for the fish, mango leaves, cayenne peppers, and used cooking oil.
Adjust the taste to your liking.
Add the fish and gently mix with your hand for 3 minutes or so.
Wrap each fish with mango leaves and place in a thick pan or clay pot (include some of the spices if you like).
Pour all the marinade on top including the cayenne peppers.
Turn heat on medium and wait for it to boil uncovered.
When it starts to boil, lower the heat to its lowest and simmer away covered for at least 1 hour or until the marinade is almost gone.
Pour the used cooking oil before transferring the dish to a plate. Add some of the concentrated oily broth.
Drizzle more used cooking oil upon serving.
Enjoy with rice with the broth drizzled on it.