Heat a pan with a tight-fitting lid. Lightly roast the cloves (if using) until fragrant. Cook tomatoes, onion and garlic in this, covered, on medium heat. Stir after 10 minutes, when the tomatoes have released a lot of juice.
Continue to cook on medium heat until the tomatoes are quite soft. This should take another 10 minutes. Remove from heat and allow to cool. Blend to obtain a smooth puree. Transfer the sauce to a deep pan and boil for a few minutes to thicken the pulp.
Blend the soaked raisins to a smooth paste. Add the raisin paste to the boiling tomato pulp. Then, add the chilli powder, pepper powder (if using) and cook for another 2–3 minutes, or until the desired consistency is achieved.
Remove from heat and keep aside to cool. Add salt and vinegar and stir. Sauce will thicken further upon cooling. Pour into a glass jar and close the lid. Store in the refrigerator for up to 2 weeks.
Makes 300 ml