Plunge live crabs into boiling water for about 3 - 4 minutes. Discard
unwanted matter of the crabs and cut crabs into large pieces. Smash
claws lightly with the opposite side of cleaver to allow flavors to
penetrate.
Put chilies onions and garlic in a blender and process for to a
paste.
Heat oil in pan/wok and saute the paste for approx. 4 minutes or until
fragrant, then stir in turmeric powder and saute for a further 1 minute.
Add in crabs and fish sauce, mix well with the combination paste, cover
and cook over medium heat for approx. 5 minutes.
Obtain tamarind juice by stirring and draining the pulp soaked in water
and pour into the crabs
Add water and garam masala and bring to boil and simmer for another 10
minutes.
Can be prepared earlier and served later. Reheat over medium heat.