Balsamic Vinegar of Modena is a Protected Geographical Indication of the European Union. That means it can only be produced exclusively in the Italian provinces of Modena and Reggio Emilia. A classic balsamic vinaigrette is a recipe everyone should have at the ready. I use a three-to-one ratio of olive oil to vinegar. This versatile vinaigrette is perfect for dressing heartier greens such as arugula or romaine, or for roasted vegetables.