When making vinaigrette, always use quality olive oil and vinegar. Vary the vinegar here, if you like. Red wine vinegar has more intensity than white wine vinegar and is good matched with more assertive herbs, such as oregano. Sherry vinegar, derived from the fortified wine, is a little stronger in character than red or white wine vinegar. Sherry vinegar has a golden hue and burnished flavor that complements roasted peppers, especially. Champagne vinegar is finer, still, with a lighter body and color. And then there is balsamic vinegar. Made from the juice of the Trebbiano grape, it has a distinctive sweet flavor and caramel color that come from aging in oak barrels. There are balsamic vinegars as rare as fine wines, with commensurate prices as well. A collection of vinegars allows for an interesting repertoire of vinaigrettes. We recommend having red and white wine vinegars, as well as balsamic, on hand as a matter of course.