In a medium saucepan, heat 2 tablespoons of the peanut oil until shimmering. Add the onion, garlic, jalapeño and ginger and cook over moderately high heat, stirring, until softened, about 5 minutes. Add the curry powder and cook until fragrant. Add the tomatoes and their juices, the coconut milk and sugar, season with salt and pepper and bring to a boil. Simmer over moderate heat, stirring occasionally, until slightly thickened, 15 minutes.
In a large skillet, heat the remaining 1 tablespoon of peanut oil until almost smoking. Add the shrimp in a single layer and cook over moderately high heat, turning once, until lightly browned but not cooked through, about 2 minutes. Add the coconut-curry sauce to the skillet and simmer until it is thickened and the shrimp are just cooked through, 3 to 4 minutes. Stir in the cilantro and serve.
Serve With: Steamed white or brown rice and lime wedges.