Blanch tomatoes and remove skins; squeeze out excess seeds.  In a large pot over medium heat, combine the tomatoes, onions, cloves, and chicken broth.  Bring to a boil and gently boil for 20-30 minutes to blend all the flavors.  Remove from heat and blend in batches (or use an immersion blender).  In the empty pot, melt margarine.  Stir in flour to make a roux, cooking until medium brown.  Gradually whisk in a bit of the tomato puree, then stir in the rest.  Season with salt and sugar and adjust to taste.