Preparation

Roast the beef

• Combine the pepper and salt on a rimmed baking sheet or cutting board. Rub the oil over the meat to coat it lightly, then roll it in the salt and pepper mixture to coat. Transfer to a rack in a roasting pan. Let sit at room temperature for 1 hour before roasting.
• Position a rack in the center of the oven, and heat the oven to 300°F. Roast the beef until an instant-read thermometer registers 110°F for rare or 115°F for medium rare, about 1-1/2 hours. Remove the roast from the oven. Let sit, tented loosely with foil, for up to 2 hours.

Make the sauce

• Up to 2 hours before serving, bring the vinegar, wine, shallot, and tarragon sprig to a boil in a 1-quart saucepan over medium-high heat.
• Turn the heat down and simmer until the liquid is reduced to 2 Tbs., about 6 minutes. Strain the liquid into a small bowl and discard the solids. If you have less than 2 Tbs. of the vinegar reduction, add enough water to equal 2 Tbs.
• Melt the butter in the microwave or on the stove over low heat. Put the yolks and vinegar reduction in a blender and blend until the yolks begin to froth. With the motor running, slowly pour in the butter and blend until thickened to the consistency of heavy cream, about 2 minutes. Add the chopped tarragon and season to taste with salt and pepper. If necessary, put the blender jar in a bowl of hot water to keep the sauce warm.

Sear the beef

• To sear in the oven: Heat the oven to 475°F. Roast until 125°F for rare or 130°F for medium rare, about 10 minutes.
• Or, to sear on the stove: Heat 2 Tbs. oil in a heavy 12-inch skillet until shimmering hot. Add the beef, and cook, turning and pressing with tongs, until browned all over and, cooked to the desired temperature, about 4 minutes per side.
• Transfer to a cutting board. Slice and serve with the sauce.

Make Ahead Tips

The beef can be roasted and then sit at room temperature, tented with foil, for up to 2 hours before the final sear.