BEURRE BLANC Nantais, now known simply as beurre blanc, is a velvety white butter sauce, traditionally made from a reduction of vinegar and shallots to which butter is added. It was created in the area of the Loire Valley between the towns of Angers and Nantes to serve with the pike, shad, and salmon that populate the Loire River.
The recipe that follows, which is based on the original and uses only vinegar, will surprise those familiar with a contemporary beurre blanc that uses wine or a combination of wine and vinegar. It is wonderful with all forms of fish. Although flavored vinegars can be used, I generally use plain white (distilled) vinegar. Freshly chopped herbs, or even puréed herbs, can be added at the end to vary the flavor and appearance of the sauce.