Martha Stewart's Bearnaise Sauce

DIRECTIONS

• Combine vinegar, wine, shallots, black pepper, and 1 1/2 teaspoons tarragon in a small saucepan.
• Cook over medium heat until reduced to 1 tablespoon, 5 to 10 minutes.
• Add egg yolks and 1 tablespoon of water to reduced vinegar mixture.
• Whisk until thick and pale, about 2 minutes.
• Set pan over moderately low heat and continue to whisk at reasonable speed reaching all over bottom and insides of pan, where eggs tend to overcook.
• To moderate heat, frequently move pan off burner for a few seconds, then back on.
• As they cook, the eggs will become frothy and increase in volume, then thicken.
• When the bottom of the pan is visible in the streaks left by the whisk and the eggs are thick and smooth, remove from heat.
• By spoonfuls, add soft butter, whisking constantly to incorporate each addition.
• As the emulsion forms, add butter in slightly larger amounts, always whisking until fully absorbed.
• Continue incorporating butter until sauce has thickened to consistency desired.
• Season with salt, remaining 1 1/2 teaspoons chopped tarragon and, if desired, pepper.
• Add a few droplets of lemon juice if necessary.