Clean fish with head on, remove gills and clean it properly. Make small slits on the fish and marinate the fish with the ingredients given in "Marinate". Keep this aside for half an hour.
Meanwhile, heat 2 tsp olive oil in a pan, saute ginger, garlic, chopped onion and chopped tomato. Add chilli powder, coriander powder, garam masala, pepper powder, curry leaves, and salt. Saute this for few minutes, till raw smell disappears. This is going to be our paste.
Heat oil in a pan, and fry marinated fish for 2 minutes on both sides. Now smoke banana leaf on flame to make it flexible. Add a spoonful of paste on the leaf, spread it and place fish over it, top the fish with another spoon of paste. Wrap the fish in the banana leaf and tie it with the cotton thread.
Again in the same oil, fry the wrapped fish for 4 to 5 minutes. Serve hot with rice.
Roast half the amount of cashew in ghee, keep it aside. Soak channa dal for 15 minutes.
Heat oil in a pan and add everything under "Tempering". Then add carrot, turmeric powder, and hing, when raw smell disappears, add rava and roast it well.
In a bowl, add curd, roasted items, broken cashews, and salt. Mix it well. Finally add baking soda, when it start frothing, add water little-by-little until it becomes idli batter consistency. Do not let anytime for setting.
Place the roasted cashew upside down on the moulds of idli plate, pour batter and steam it for 8 to 10 minutes.