It you have time, thaw the roast and set it on a rack over a plate in the fridge for 3 days. Trim away any leathery, dry bits. This gives the best flavor with the most tenderness.
Adjust the oven rack to the lower-middle position and heat the oven to 250F. Season the roast liberally with salt and pepper to taste. Heat the oil in an ovenproof Dutch oven or heavy-duty roasting pan over medium-high heat until just smoking. Sear the roast until well browned, about 2 minutes on each side.
Transfer the pot to the oven and cook, uncovered, until an instant read thermometer inserted into the thickest part of the meat reaches 120F for rare, 125F for medium-rare, or 130F for medium, 10-20 minutes longer. Remove the roast from the pot and transfer to a cutting board. Tent the roast loosely with foil and let stand for 20 minutes. Cut crosswise into thin slices and serve.