This recipe and others can be found in the 12-part illustrated series "A World of Curries". You can read all about this unique Indian flavor here.
1/2 cup tamarind pulp
3/4 cup water
4 green chiles such as jalapeños, seeds and stems removed, sliced into rings
1 cup chopped shallots
5 cloves garlic, minced
2 tablespoons finely chopped fresh ginger
3 tablespoons vegetable oil
1 teaspoon ground cayenne
1 3-pound chicken, skinned, boned, and cut into 1-inch cubes
1 1/2 cups coconut milk, see recipe here
4 green New Mexican chiles, roasted and peeled, stems and seeds removed, chopped
Soak the tamarind in 3/4 cup boiling water for 15 minutes. Mash the tamarind and then strain. Discard the pulp and reserve the juice.
In a large skillet, saute the chile rings, shallots, garlic, and ginger in the oil until soft. Stir in the cayenne and chicken and mix well.
Add the coconut milk and bring to a boil. Reduce the heat and simmer, covered, stirring occasionally, for 20 minutes.
Add the chopped chile and cook for an additional 5 minutes. Stir in the tamarind and cook, uncovered, for 10 minutes or until the sauce is thickened, stirring occasionally.