The original version, from Brittany, is almost always prepared with Muscadet wine, which is made from grapes grown in the area surrounding the city of Nantes on France’s Atlantic coast. Muscadet has the crisp, clean flavor and the acidic edge essential to a successful beurre blanc. If Muscadet is unavailable or too expensive, other wines can be used, but if only wines containing relatively little acidity are available, it may be necessary to add a few additional drops of vinegar to wake up