Grind the grated coconut, green chillies to a paste and keep aside.
Grind cinnamon stick, cloves,cardamoms,black pepper to fine powder and set aside.
Clean the crabs and cut them. Add ½ tsp salt and keep aside.
Heat oil in a deep pan. Add chopped onions and fry till golden brown.
Add ginger garlic paste and curry leaves, sauté for a minute.
Add chilli powder, coriander powder, turmeric powder.
Now add the crabs and mix well to coat them with the masala.
Add salt to taste and some water, cover and let it cook for 5 minutes.
Add the ground paste and powdered spices. Let the gravy simmer for 10 minutes.
Finally add chopped coriander leaves and switch off. This curry goes well with steamed white rice or roti.