The classic French vinaigrette is composed of three to four parts oil slowly whisked into one part acid (usually wine vinegar) seasoned with salt and freshly ground pepper. Because the addition of oil slows down the infusion of flavor, any seasoning, even the basic salt and pepper, should be added before the oil. Using fine quality oils and vinegars allows such a simple combination to be sublime. A vinaigrette can also contain prepared mustard, which not only adds zest but helps create emulsification. Chopped shallots or garlic and fresh herbs can also be incorporated for added flavor. Any additions should be made before the oil is integrated.