The ultimate sauce for filet mignon or any great steak—it’s rich and buttery.
- 1/4 cup sherry vinegar, such as Pedro Ximénez Reserve
- 1 shallot, peeled and minced
- 1/2 teaspoon freshly ground black pepper
- 1 tablespoon fresh tarragon leaves, chopped, or 1 teaspoon dried tarragon
- 2 egg yolks
- 1 tablespoon water
- 6 ounces unsalted butter
- Coarse salt to taste
In a small saucepan, bring the vinegar, shallot, black pepper, and tarragon to a boil. Lower the heat and cook until the vinegar is reduced by half. Pour into the top of a double boiler (or a metal or heatproof glass bowl that will fit over a saucepan), allow to come to room temperature, and then whisk in the yolks and the water.
Melt the butter, and set aside. Fill the bottom of the double boiler or saucepan with 2 inches of water, bring to a boil, and then lower the heat to a simmer. Place the top of the double boiler or the bowl over the simmering water and whisk the mixture until it doubles in volume.
Slowly whisk in the butter, about 2 tablespoons at a time. Continue whisking vigorously until the sauce becomes thick but still pourable. Taste, and season with salt if desired. Remove the double boiler from the heat. The sauce can sit while you cook your steak. Whisk it gently before serving if needed.
Yields about 1/2 cup.