Béarnaise Sauce

Sauce Béarnaise (warm tarragon-butter emulsion) teaches the essential truth of every warm emulsion: the heat must be steady enough to thicken the yolks, yet gentle enough to keep them supple. Béarnaise should arrive glossy, herb-flecked, and tepid. Make it truly hot and the butter escapes from the yolks.

The book's small stewpan assumed a saucier free to whisk without interruption over a low flame, with a tammy ready and service waiting nearby. This entry asks for neither a stockpot nor a salamander, only that saucier's attention. At home, a bain-marie gives gradual heat and a fine-mesh sieve replaces the tammy. The five-yolk formula becomes three yolks, with every weight carried at three-fifths and only tiny spoon measures rounded to what a home spoon can honestly measure. Quantity, direct flame, and brigade holding are scaffolding. The vinegar reduction, gradual liaison, and tepid service are the dish. One cook, one stove, one evening.

The reduction smells almost too sharp before the butter enters, which is exactly right. It must carry enough vinegar, tarragon, and chervil to remain vivid beneath the richness. The step that decides everything is adding the melted butter gradually while keeping the yolks warm enough to bind and cool enough not to scramble.