How to Make It
In a saucepan, heat the oil. Add the onion and garlic and cook over moderately low heat, stirring occasionally, until softened, about 7 minutes. Add the brown sugar, paprika, allspice and cloves and cook, stirring occasionally, until the sugar melts. Add the vinegar and tomato paste and cook over moderate heat until thick, about 3 minutes. Stir in the tomato sauce and simmer over moderate heat, stirring occasionally, until very thick, 15 to 20 minutes.
Transfer the ketchup to a blender or food processor and puree until smooth. Season with salt and pepper.