In a saucepan, heat the oil and sweat the onions with the salt.
When translucent, add the garlic, eggplant or zucchini, and bell peppers. Cook until soft and thoroughly cooked.
Add the diced tomatoes (and chili pepper if desired) and mix well. Bring to a boil, reduce heat, and simmer for about 20-30 minutes until the tomatoes are thoroughly cooked and reach the desired texture (more or less reduced, according to your taste).
Meanwhile, prepare the pesto by mixing the herbs with the grated cheese and oil. Set aside.
When the vegetable sauce is cooked and the texture is to your liking, add the parsley and half of the pesto.
Taste and gradually add more pesto to taste. Also adjust the salt and acidity, if needed, with a touch of vinegar.
