Complex sentence: The U.S.-style Italian dressing is unknown in Italy, where salad is normally dressed at table with olive oil, vinegar, salt, and sometimes black pepper, and not with a pre-mixed vinaigrette.
Split into simpler sentences: The U.S.-style Italian dressing is unknown in Italy. Salad is normally dressed at table with olive oil, vinegar, salt, and sometimes black pepper, and not with a pre-mixed vinaigrette.