- 1 small shallot, chopped
- 1 1/2 teaspoons chopped fresh tarragon or 1/2 teaspoon dried
- 1/4 cup plus 1 tablespoon white wine vinegar
- 2 egg yolks, beaten with 1 tablespoon water
- 1 stick butter, softened, cut into small pieces
To make sauce: In a double boiler (or heatproof bowl set over, but not touching, a sauce pot of simmering water), combine shallot, tarragon, and vinegar. Cook 5 minutes, until most of the vinegar has evaporated. Whisk in egg yolk mixture.Whisk continuously until egg yolks have thickened, about 5 minutes. Whisk in butter gradually, piece by piece, until incorporated (sauce should have the texture of mayonnaise). Remove from heat. Season to taste with salt and pepper.