Roast all the whole spices on a pan on medium heat. Switch off the flame once you get the aroma of the spices and let it cool.
Meanwhile, take a deep dish, marinate the cleaned and cut crab with curd, chilli powder and salt. Keep aside. You may view my video on how to clean a crab by clicking the video link here.
Grind all the roasted ingredients into a smooth paste along with ginger, garlic, onion, tamarind, jaggery and a little water. Season with salt, as per taste.
Heat some ghee in a nonstick pan. Saute the ground masala on slow flame for 15-20 minutes or till the ghee begins to separate from the masala.
Now add the marinated crabs. Cover the pan with a lid and let it cook on medium flame for 10-15 minutes.
Add the curry leaves.
The final texture of the end-product shall be like a paste on the Crab