ΒΌcupwhite wine or cider vinegar(substitute a splash of white balsamic, optional)
1small shallot, peeled and finely minced
1tbspfresh tarragon (or 1 tsp dried)
2egg yolks
12tbspunsalted butter
salt and freshly ground pepper, to taste
dash of lemon juice (optional)
Instructions
In a heat proof cup or bowl, melt butter in microwave (approx. 2 minutes at 30%)
Combine vinegar, shallots, and tarragon leaves in a small saucepan. Over a medium flame, bring just to a boil, and then reduce heat to low. Simmer until there are only a few tablespoons of liquid left, approximately 5 minutes. Remove from heat, and set aside to cool.
In the bottom of a double-boiler, heat water to boil.
In the bowl of the double-boiler, put the cooled vinegar mixture. Add a tablespoon of water and the egg yolks, then whisk to combine.
Reduce heat to very low and put the double-boiler bowl over the boiling water, making sure that it does not touch the water directly. Continue to whisk the yolks until they thicken, approximately 5 to 7 minutes.
Slowly pour in the butter, a tablespoon or two at a time, whisking slowly and constantly to combine and emulsify. Remove the bowl from the pan occasionally, so as not to overcook the eggs. Slowly beat in the butter, a tablespoon or two at a time, whisking slowly to combine and emulsify. Remove the bowl from the pan occasionally, so as not to overcook the eggs, and taste the sauce.
Remove from heat when all the butter has been incorporated. Season with salt. If the flavor is not sharp enough, add a splash of lemon juice. If the sauce is too thick, stir in a splash of hot water. Add up to a teaspoon of fresh tarragon leaves (1/2 tsp of dried), and serve.
Reduce vinegar, tarragon, and shallots to a few teaspoons and cool. Combine vinegar mixture, egg yolks, and salt and pepper over double-boiler; slowly whisk in butter until emulsified. Season with salt, pepper, and additional tarragon.