Hollandaise Sauce

Hollandaise is a warm butter emulsion that requires the egg yolks to be taken to a specific stage before the butter goes in. The yolks and a reduction of white wine vinegar are whisked in a bowl over barely simmering water, not touching the water, until the mixture is pale, thick, and falls in a continuous ribbon from the whisk. At this stage the yolks have coagulated enough to hold the butter in suspension. Clarified butter goes in drop by drop at first, then in a slow, thin stream as the emulsion stabilizes. The heat must stay low throughout. Too hot and the yolks scramble; too cool and the butter does not emulsify. The finished sauce is held warm, not hot, covered, over the same water bath. Hollandaise does not survive reheating. There is no rescue once the emulsion breaks or the yolks scramble. The egg yolk is both the thickener and the emulsifier, providing lecithin to hold the fat in suspension and protein to give the sauce its body.