ROASTED BEEF TENDERLOIN WITH CORNICHON TARRAGON SAUCE (for six)
a 3 to 3-1/2 pound fillet of beef, tied, at room temperature
2 tablespoons vegetable oil
6 tablespoons (1/3 cup) unsalted butter, softened
4 tablespoons Dijon-style mustard
1/3 cup plus 2 tablespoons minced shallot
1-1/2 cups dry white wine
2-1/2 tablespoons minced fresh tarragon leaves
2 tablespoons heavy cream
14 to 15 cornichons (French sour gherkins)
1. In a bowl with an electric mixer cream together the butter and the mustard.
2. In a large saucepan combine the shallots, the wine and the tarragon and cook the mixture over moderately high heat until the wine is reduced to about 1/3 cup. The mustard butter and the shallot mixture may be made 1 day in advance and kept covered and chilled. Reheat the shallot mixture before continuing.
3. Remove the fillet from the refrigerator and let sit at room temperature for about an hour before roasting. Meanwhile, position a rack in the center of the oven and heat the oven to 375*. Rub the fillet with the oil, season it with salt and pepper and, in a roasting pan, roast it for 40 to 50 minutes, or until an instant read thermometer inserted in the center reads 120*F for rare, 125*F to 130*F for medium rare, or 135*F for medium. Transfer the fillet to a platter and let it stand, covered loosely with foil, for 15 minutes.
4. Add the cream and the cornichons to the warm shallot mixture, reduce the heat to low, and whisk in the mustard butter, a little at a time, and any meat juices that have accumulated on the platter. Season the sauce with salt and pepper and keep it warm, but do not let it boil.
5. Slice the fillet and nap it with the sauce.