(I got this one off some Sri Lankan website, but it is really good. You can probably find most of the spices and such in an Indian grocery)

1 lb. shrimp, peeled and de-veined
2 onions, finely chopped
½ c. chopped tomato
2 cloves garlic, finely chopped
1 in. piece of ginger, peeled and chopped
5-6 curry leaves
juice from 1 lime
2 tsp. cayenne powder (or some other hot chili)
½ tsp. turmeric
1 tsp. black mustard seeds
½ tsp. cumin seeds
salt to taste

Crush the ginger and garlic with the cumin and mustard seeds. Set aside.
Fry the onion and curry leaves in a bit of oil until the onion is golden. Add the tomato, cayenne, and turmeric with about ¼ c. water and cook until the tomatoes are soft. Add the crushed spices and fry about 5 minutes. Add the shrimp and salt and mix well. Add enough water to just barely cover and simmer 10 minutes. Add the lime juice and cook until the sauce is slightly thickened. Serve with rice.

{via Kathy}