Marinate the prawns with yogurt, onion paste, ginger paste, garlic paste, red chilli powder, turmeric powder, a pinch of salt and 1 tbsp mustard oil, keep aside for at least 30 minutes.
Now add the cashew-nut paste and poppy-seed paste to the prawns, mix well, keep aside for another 15 minutes or so.
Heat the remaining oil in a thick bottomed pan, when smoking hot, throw in the crushed cinnamon, cardamom, cloves and bay leaves. Allow the whole spices to splutter.
Once the spices have released their aroma, add the sliced onions, fry till golden brown.
Add the marinated prawns along with the marinade. Cook over a low flame till oil starts to separate from the masala.
Add 1/4 a cup of warm water, give it a gentle stir.
Throw in the slit green chilies, adjust seasonings, continue to cook over a low flame for a further 5-7 minutes or so till the gravy thickens to a coating consistency.
Finish with a sprinkle of garam masala powder and a dollop of ghee.
Serve hot with rice.