Clean and soak rice for 1/2 an hour.
Grind together ginger, green chillies, garlic, 1/2 of onion, coriander powder, 3/4 of coriander leaves and salt to a fine paste.
Marinate the cleaned prawns with the above mixture at least for 15 mins.
Heat oil and ghee together in a heavy bottom vessel.
Add crushed spices, cashewnuts, mint leaves and onion and saute, till it becomes golden brown.
Add tomatoes and cook, till it becomes soft.
Add the marinated prawns.
Add turmeric powder and saute, till the oil separates.
Add rice to it.
Add 3 cups of water and salt.
Close the vessel with a tight lid and cook for 10 - 15 mins.
:- If preparing in a pressure cooker, cook for 1 whistle.
Garnish with the remaining coriander leaves.