Sofrito is heavily emphasized as the third critical component in a "sofregit" base along with tomatoes and onions. Garlic is optional, as it is not considered an integral part of the standard "sofregit" recipe. Some "sofregit" recipes do not contain tomatoes at all, but are made more complex with the addition of diced vegetables such as leeks or bell peppers. In Italian cuisine, chopped onions, carrots and celery is battuto, and then, slowly cooked in olive oil, becomes "soffritto". It is used as the base for most pasta sauces, such as arrabbiata sauce, but occasionally it can be used as the
Spaghetti alle vongole but with tomatoes and fresh basil, the addition of tomatoes being more frequent in the south. Traditionally, the bivalves are cooked quickly in hot olive oil to which plenty of garlic has been added. The live clams open during cooking, releasing a liquid that serves as the primary flavoring agent. The clams are then added to the firm pasta (spaghetti, linguine, or vermicelli), along with salt, black pepper (or red pepper), and a handful of finely chopped parsley. In the Liguria region of Italy, east of Genoa, "Spaghetti alle vongole (veraci)" means spaghetti with tiny baby clams in the shell,