Beurre blanc

From the Lexicon, Reduction, Nappe & Mounting

REDUCTION: simmering a liquid to evaporate water, concentrating flavor and body, the sauce-maker's primary move, always reduced BEFORE final seasoning (salt concentrates too). NAPPE: the classical doneness test: sauce coats the back of a spoon and holds a clean line drawn by a finger. MONTER AU BEURRE: 'mounting' cold butter cubes into a finished sauce off the heat, swirling, emulsifying in gloss, body, and richness; the last thirty seconds that make restaurant sauces taste like restaurant sauces. Together they are the grammar of à-la-minute saucing: reduce, season, mount, plate.