Step 1

Preheat the oven to 400°F.

Step 2

Boil the red wine, vinegar, shallot, peppercorns and thyme in a saucepan over high heat until reduced to 1/2 cup, about 10 minutes. Set the wine reduction aside.

Step 3

Generously season the tenderloin on all sides with salt and pepper. Heat the oil in a large roasting pan over high heat. Carefully add the tenderloin to the roasting pan, then transfer the pan to the oven and roast the tenderloin, turning every 5 minutes, for 15 to 20 minutes, or until a meat thermometer registers 120°F for medium-rare.

Step 4

While the tenderloin is roasting, finish the sauce by gradually whisking the cold butter into the warm sauce until it is fully emulsified. Strain the sauce through a fine-mesh sieve into a small saucepan. Season the sauce to taste with salt andpepper; keep warm.

Step 5

Remove the roasted tenderloin from the oven and let it rest for at least 5 minutes (the meat will continue cooking at this time). Transfer the rested tenderloin to a cutting board and slice it crosswise. Arrange the sliced tenderloin on a large platter. Pour any of the juices from the roasting pan into the butter sauce and serve immediately with the tenderloin.