Goan Shrimp in Roasted-Coconut Sauce

Ingredients

• 1 pieces piece cinnamon stick (1-inch)
• 1 teaspoon coarse sea salt such as fleur de sel 
• 1 teaspoon coriander seeds 
• 0.5 teaspoon cumin seeds 
• 3  garlic cloves finely chopped
• 1 tablespoon ginger grated peeled (use a Microplane)
• 8 inch chiles fresh green hot cut lengthwise into thin shreds, plus seeds
• 1 medium onion finely chopped
• 1 cup plum tomatoes finely chopped (1 large)
• 1 teaspoon red-pepper flakes hot
• 2 teaspoons red-wine vinegar 
• 1.5 lb shrimp peeled
• 0.3 cup swad-brand tamarind concentrate (see cooks' note, below)
• 0.5 teaspoon turmeric 
• 0.3 cup coconut or dried unsweetened grated
• 3 tablespoons vegetable oil 

Equipment

• bowl
• frying pan
• sieve

Directions

1. Toast coriander, cumin, cinnamon, and cloves in a small heavy skillet over medium heat, shaking skillet, until fragrant and darker (do not burn), 3 to 4 minutes. Stir in coconut, red-pepper flakes, and turmeric and cook, stirring, until coconut is golden brown, 1 to 2 minutes.
2. Transfer to a bowl and cool completely, then pulse in grinder until finely ground.
3. Heat oil in a 12-inch heavy skillet over medium-high heat until it shimmers, then sauté onion until golden, 3 to 5 minutes.
4. Add garlic, ginger, chiles, tamarind, and spice mixture and cook, stirring, 30 seconds.
5. Add tomato and cook, stirring, until sauce is thickened, 3 to 4 minutes.
6. Toss shrimp with sea salt, then add to sauce and cook, stirring, until just cooked through, 3 to 5 minutes. Stir in vinegar and season with sea salt.
7. If you can't find tamarind concentrate at your Asian market, use 3 tablespoons tamarind pulp (from a pliable block) softened in 6 tablespoons hot water, stirred into a paste, then forced through a sieve.