How to Make It
In a spice grinder, combine the coriander, cardamom and anise seeds with the clove, crushed red pepper, cinnamon and peppercorns and grind to a fine powder. Transfer to a small bowl and stir in the oil, vinegar, ginger, garlic and turmeric. Season the masala paste with salt.
In a large skillet, heat the oil until shimmering. Add the curry leaves and cook over moderately high heat until they sizzle, about 10 seconds. Add the garlic, onion and ginger and cook over moderate heat, stirring occasionally, until softened and starting to brown, about 10 minutes. Add the masala paste and cook, stirring, until fragrant, about 5 minutes. Add the tomatoes and their juice and cook, scraping up any browned bits from the bottom of the skillet.
Add the shrimp to the skillet in an even layer and season with salt. Simmer, turning once, until just cooked through, about 3 minutes, then serve.