Grind the ginger, garlic, green chillies, peppercorns and fennel coarsely. Keep aside.
Heat oil in a pan.
Add the curry leaves followed by onions. Saute till slightly brown in colour.
Add the ground paste and saute till the raw smell goes.
Add the coriander, chilli and turmeric powders and fry for a minute.
Tip in the chopped tomatoes and saute till oil separates.
Add the crab pieces along with some salt.
Cover and cook on low heat till the crab releases its juices. Give a stir occasionally.
Take the lid off and cook further till the masala dries a bit and coats the crab pieces evenly.
You may drizzle a bit of oil along the sides, if you want to fry it more.
Serve hot with rice.