In a large skillet, heat 1 tablespoon vegetable oil over medium. Add the onion and sauté, stirring occasionally, until softened, about 5 minutes, add the garlic and sauté for 1 minute. Add the brown sugar and cook, stirring occasionally, until the onion and garlic are caramelized, about 5 minutes. Stir in curry powder, paprika, cinnamon and cook until just fragrant, about 1 minute. Stir in the tomato paste, then add the chopped tomatoes and their juices, stock and vinegar. Cook, stirring occasionally, until thickened, 10 to 15 minutes.