Wash and cut tomatoes into quarters. Peel, wash and chop garlic. Peel, wash and cut carrots into roundels. Wash and finely chop celery. Peel, wash and slice onion. Wash basil leaves and cut into thin strips. Heat oil and butter in a pan, add bay leaf, peppercorn, sliced onions and sauté until translucent.
Add the chopped garlic and celery, stir-fry briefly. Add carrot roundels and tomatoes, stir-fry for a minute and add three cups of water. Bring it to a boil. Cook for ten to fifteen minutes covered with a lid. Strain the blended mixture through a strainer. Reserve the liquid. Remove peppercorns and bay leaf from the residue and allow it to cool.
Blend in a mixer to get a smooth puree. Pass it through a sieve or strainer. Add the reserved liquid to the pureed tomatoes and adjust the consistency. Put it back on heat. Add salt, freshly crushed peppercorns and let it simmer for a couple of minutes. Just before serving, add the basil leaves.