1Heat 3/4 pound butter until barely melted and set aside.
2Combine 2 tablespoons white wine, 3 tablespoons chopped fresh tarragon (or 1 tablespoon dried tarragon), 2 chopped shallots, 2 tablespoons tarragon vinegar or red wine vinegar, and salt and black pepper to taste in a small nonreactive pot. Boil slowly until almost all the liquid has cooked away, leaving a moist paste. Cool.
3Transfer the paste to the top of a double boiler with boiling water in the bottom portion. Whisk in 4 egg yolks and 2 tablespoons water. Heat, whisking constantly, until the mixture is fluffy and thickened.
4Remove the top of the double boiler from the heat and beat in the melted butter very slowly, whisking constantly. Correct the seasonings and keep the sauce warm over steaming water until ready to serve over chicken, fish, or steak.
This recipe, while from a trusted source, may not have been tested by the CHOW food team.