Sauce Bearnaise

Sauce bearnaise is a warm emulsion sauce, a daughter of hollandaise, made by emulsifying clarified butter into egg yolks over gentle heat, with a reduction of white wine vinegar, shallots, and fresh tarragon providing the aromatic base. The sauce is named for the Bearne region of southwest France, the homeland of King Henri IV, who was said to favor tarragon and shallot flavors. The most often cited attribution credits the chef Collinet, who is said to have invented the sauce at his restaurant Le Pavillon Henri IV in Saint-Germain-en-Laye, near Paris, in 1836. The dating and attribution are plausible but not firmly documented; what is certain is that the sauce was well established in the French repertoire by the late nineteenth century and codified by Escoffier. It is the canonical sauce for grilled or roasted red meat, particularly steak.

A spoonful of bearnaise is a pale yellow, glossy, spoonable emulsion, with a rich, buttery mouthfeel and a clear, bright aromatic of tarragon and shallot cutting through the richness. The sauce is warm and fluid but not hot; it should hold its shape briefly on the meat, then melt into a glossy film. The acidity of the vinegar reduction balances the butter, while the tarragon contributes its characteristic anise-like note. Eaten on steak, it is the classic match.

Bearnaise rests on two mechanisms: a vinegar-shallot-tarragon reduction and a warm butter-in-yolk emulsion. The reduction — white wine vinegar, shallots, and tarragon, simmered until nearly dry — concentrates the aromatic compounds (the terpenes of tarragon, the sulfur compounds of shallot) and the acidity into a small volume of intense liquid; this reduction is folded into the egg yolks before the emulsion begins. The emulsion itself is built like hollandaise: clarified butter is added to the yolks drop by drop over a pan of warm water, with the lecithin in the yolks emulsifying the butterfat into a stable suspension of tiny droplets. The temperature must stay below the point at which the yolks would scramble — around sixty-five degrees — but warm enough that the butter stays liquid; this narrow window is what makes the sauce technically demanding. If the emulsion breaks, it can often be re-established by whisking in a fresh yolk or a splash of warm water.