Place crabs in boiling water for 5 minutes, then remove and clean. Break the crab into desired portions and crush the shell a bit so flesh can be more easily removed. Slice the shallots and chillies, grind garlic and ginger and grate the coconut. Place the crab in a pan and add the shallots, chillies, garlic, ginger, turmeric, fenugreek, chilli powder, paprika powder, cinnamon stick, curry powder, curry leaves, coriander leaves and thin coconut milk and cook until crabs are done. Mix the thick coconut milk with the lime juice, salt, grated coconut and the ground rice and add to the pan. Stir and simmer for approximately 10 minutes. Remove the cinnamon stick before serving.