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.