1. Sauté the chopped vegetables in a large saucepan with olive oil.

2. When the vegetables are wilted, add the chopped tomatoes, cloves, bay leaves, and continue cooking over moderate heat, skimming occasionally.

3. When the tomatoes have lost most of their water, add all the other ingredients.

4. Season very lightly because the sauce tends to shrink when cooking.

5. Stir with a wooden spoon and let it simmer over very low heat for at least 3 hours, stirring frequently.

6. When the sauce has thickened, strain it through a very fine sieve, leaving the bay leaves and cloves, and collect it in another saucepan.

7. Taste the sauce and, if necessary, add more salt and pepper.

8. Put the sauce back on moderate heat and let it simmer gently for another ten minutes.

9. Pour the sauce into jars with airtight lids.