With so many brands making this beloved salad olive oil and balsamic vinegar marinade, it helps to know how to spot the healthiest ones. What makes a good balsamic vinaigrette? Well, it turns out, the perfect version of this popular salad dressing is truly a wonder of cooking technique, high-quality ingredients from around the world, and science coalescing. Optimally, tart balsamic vinegar from Italy, tangy mustard from Dijon, olive oil from the first cold press, and various spices meld together in an emulsion created by the marriage of oil, water, and acid.