Beurre blanc

Beurre blanc ("white butter" in French) or Beurre Nantais is a warm emulsified butter sauce made with a reduction of vinegar and/or white wine (normally Muscadet) and shallots into which softened whole butter is whisked in off the heat to prevent separation. The small amount of emulsifiers naturally found in butter, including a trace of lecithin, is used to form an oil-in-water emulsion. Although similar to hollandaise in concept, it is considered neither a classic leading nor compound sauce. This sauce originates in the cuisine of the Loire-Atlantique department.