Serve rich, creamy potato gratin with this simple roast beef and lively piquant topping.
1 4-pound beef tenderloin roast tied with butcher twine every 1 1/2 inches
Salt and ground black pepper
1 fresh horseradish root, peeled and grated to yield 2 cups
1/2 cup chopped fresh parsley
2 tablespoons fresh lemon juice
Adjust oven rack to lower-middle position and heat oven to 425 degrees.
Heat a heavy-duty roasting pan large enough to accommodate the roast over two burners turned to medium-high heat for 5 minutes. While pan is heating, rub roast with oil to coat and sprinkle generously with salt and pepper. When pan is very hot, add roast and sear until well browned, about 2 1/2 minutes per side for a total of 10 minutes. Remove roast from pan. Set a wire rack in the roasting pan and place roast on rack. (Can be left at room temperature up to 2 hours before roasting.)
Roast tenderloin until a meat thermometer registers 125 degrees for medium-rare and 130 for medium, 40 to 45 minutes. Remove roast from oven and let rest for 15 minutes.
While tenderloin roasts, mix horseradish, parsley, lemon juice and a generous sprinkling of salt and pepper in a medium bowl; set aside. When ready to serve, cut tenderloin into 1/2-inch thick slices, top with horseradish mixture, drizzle with pan juices, and serve immediately.