Whisk butter into a little simmering water and—poof!—you've got beurre monté: liquid silk that pairs with any seasoning and gilds everything it touches. Beurre monté, emulsified melted butter, is a classic French preparation that can be drizzled over cooked meats, vegetables, pastas, and other dishes to add richness and a glossy appearance or used as a rich, creamy sauce base for pairing with a wide range of savory or sweet seasonings. Vigorously whisking cold butter into a measured amount of simmering water broke up the butterfat into tiny droplets that dispersed throughout the water, establishing a thick, creamy emulsion. Whisking stone-ground mustard into the beurre monté produced a bold, rich, easy-to-make sauce.