Grind together all the ingredients(except tomatoes) in a mixer grinder.
Heat gingelly oil in a pan or a kadai.
Add curry leaves and masala paste.
Add tomatoes and fry well along with the masala, till it gets cooked.
Add the crab and mix it well with the masala, till it gets set.
Add hot water into it.
When the whole thing gets fried, add thick coconut milk.
Cook again.
When it gets dry, the crab is done.
:- Serve with rice and bread.
:- Get a bigger crab for more flesh. It will taste better.