Clean the prawns and cook it in a little water with half amount chilli powder and turmeric powder and salt till it changes color to white. Keep aside.
Heat oil in a non stick pan. Add chopped onion, garlic, cloves, cinnamon ticks, cardamom, and saute till onion becomes transparent. Then add the soaked rice and saute for 2 minutes.
Add remaining chilli and turmeric powder along with 4 cups of water and salt to taste. Let it cook on a low flame till the water is almost absorbed, stirring constantly to avoid burning.
Add the grated coconut and the cooked prawns and mix well. Remove from heat after 2-3 minuutes when rice is done. Serve hot.