5 tablespoons of olive oil2 medium carrots, cut into pieces1 and 1/2 lbs of whole ripe tomatoes1 medium yellow zucchini, cut into pieces with peelThe white part (shaft) of 1 leek, cut into pieces4 sprigs of fresh basilSalt (to taste)Pepper (to taste)1 liter of chicken broth or natural vegetable brothMozzarella cheese (to taste), cut into cubes