This shrimp curry over basmati rice incorporatesthe bright-yellow spice turmeric, as domany curries; coconut milk and tamarindgive it a distinctive flavor.
Finely grind coriander, cumin, and peppercorns in a coffee or spice grinder; transfer to a bowl. Stir in paprika, cayenne, and turmeric. Process ginger, garlic, and 1/4 cup water in a food processor until smooth; stir into spices.
Heat oil in a large Dutch oven over medium-high heat until hot but not smoking. Add onion; cook, stirring often, until translucent, about 5 minutes. Add spice paste; cook, stirring, 2 minutes. Add 1 1/4 cups water; bring to a simmer.
Reduce heat to medium-low. Cover; simmer 10 minutes. Uncover. Stir in coconut milk, salt, and tamarind. Simmer until thickened, about 30 minutes.
Stir in the shrimp and basil, and simmer, stirring occasionally, until shrimp are cooked through, about 8 minutes. Serve immediately over rice.