Was the rice and soak covered in water for 20 minutes. Then drain the rice completely.
Sprinkle a little salt (no more than 1/4 tsp) and turmeric on the prawns, mix and set aside.
Grind the coconut and all the other masala ingredients to a thick, smooth paste in using a little water.
Take a large, flat, thick-bottomed pan (so that things don't stick and burn), heat 2 tbsp ghee on medium flame and fry half the curry leaves and all the onions till slightly golden.
Add the coconut masala and saute of low heat for 3-4 minutes, stirring constantly. Then tip in the prawns and mix to coat the prawns with masala.
Cook for 4-5 min and add the yoghurt and cook for a further minute. Then remove the prawns and set aside.
Now add the remaining tbsp of ghee on a low flame and add the bay leaves, cinnamon, cloves, cardamom, cumin and peppercorns. Let them fry for a few seconds and add the rice.
Saute the rice for about 7 minutes till the grains are nice an toasty.
Add the remaining curry leaves and prawns and mix with the rice and spread to create and even layer.
Pour in the coconut milk and just enough water to cover the rice and prawn mixture. Season with salt and gently swirl to mix it in.
Cover the pan with a tight-fitting lid and cook on a low-medium flame (without opening) for 20 minutes. Then, switch off the stove, move the pan to a cooler surface and let it rest for 15 minutes.
Open the lid after 15 minutes, gently fluff the rice with a fork and serve the pulao hot.