Martha's version of this classic French sauce is adapted from one chef Kerry Simon made for her.
- 2 shallots, finely chopped (1/4 cup)
- 1/2 cup white wine
- 1/2 cup champagne vinegar
- 1 tablespoon plus 1 1/2 teaspoons chopped fresh tarragon
- Salt and freshly ground pepper
- 3 large egg yolks
- 1 to 2 tablespoons warm water
- 2 sticks cold unsalted butter, cut into small pieces
- 1 1/2 teaspoons chopped fresh chervil
Combine shallots, wine, vinegar, 1 tablespoon tarragon, and 2 pinches pepper in a small saucepan set over a pot of simmering water. Cook until mixture is reduced to about 2 tablespoons. Set aside to cool.
In another saucepan, beat egg yolks with 2 tablespoons water over low heat until they become thick and foamy, 2 to 3 minutes. Add butter, about a tablespoon at a time, whisking. Add chervil and the remaining 1 1/2 teaspoons tarragon and cook until the mixture thickens and increases in volume.
Pour the cooled shallot mixture through a sieve into the thickened sauce, discarding solids. Season with salt and pepper, and stir to combine.
SourceMartha Stewart's Cooking School