Remove the claws very carefully. If you are a beginner, use kitchen gloves as a precaution.
Next take out the legs.
Press hard at the very bottom to crack open the shell.
Remove the hard outer shell completely and use the flesh.
Pour 1/2 cup of water in a large pan and add the crab pieces, green chillies, minced ginger, salt, kokam/tamarind and cook on low flame for 5-7 minutes or until the water evaporates. Keep aside (Do not overcook the crab).
In a large non-stick skillet, heat 2 tbsp of oil and add the mustard seeds and curry leaves. When the seeds start to sputter, add the chopped shallots and garlic and fry well until golden brown.
Add turmeric powder, red chilli flakes and pepper powder and cook for another 2 minutes.
Add the crab pieces and cook for 2-3 minutes to allow the flavours to blend well.
Serve hot with rice and dal or any curry of your choice.