Combine the masala ingredients for the fish, marinate it for a minimum of an hour.
Shallow fry the fish till done. Keep aside 3-4 small pieces in the fried oil itself for crushing into the masala. Remaining can be drained on a kitchen towel and set aside.
Heat oil in a big saucepan. Add the onions and chillies and saute till soft.
Add the ginger and garlic pastes and cook for a couple of minutes till the raw smell is gone. Now add in the tomatoes and cook till the tomato is completely mashed.
Add the masala powders and cook for another 5 minutes.
At this stage, add the crushed fish along with the oil into the masala and cook on simmer for another 5 minutes. The masala will be quite dry. Switch off and set aside.
Now let's make the rice - or do it side by side along with the masala! :) In a big pan, heat ghee. Fry the whole masalas till a nice aroma comes (I love this stage!)
Add the basmati rice and roast for around 5 minutes or till crisp.
Add in the hot water (ensure that the water is hot!), adjust salt and increase the flame to high till the water boils.
As soon as the water boils, reduce to minimum and keep on closed lid for 10 minutes till the rice is done. It is not necessary that the rice needs to be fully cooked. When the water is gone completely, switch off the flame. You may get a grain bite in your rice, which is OK!
For the dum ingredients, heat ghee in a kadai. Fry the onions with a pinch of salt till brown. Drain and set aside. Fry the raisins till puffed, and then the cashews till brown.
Now let us layer the biriyani. On top of the masala, sprinkle half of all the dum ingredients.
Layer in the rice completely. Sprinkle the remaining dum ingredients along with the ghee used for frying the dum ingredients. Top with the fried fish pieces.
Seal tightly with aluminium foil and close the lid. Keep on top of a hot chapathi tawa on low flame for around 15 minutes. Switch off and keep as such till serving time.
For serving, take out the fish onto a plate. Mix the rice well. Serve hot with chammanthi and pickle