Aitchbone is a cut of beef taken from the rump area of the cow, and it includes an almost wishbone-shaped bone through the piece of meat. Aitchbone beef isn't quite as tender or well marbled as sirloin or round roast, but the lean meat is flavorful, and better for you because it contains less fat. Aitchbone beef roast should be cooked slowly to retain as much moisture as possible. For best results, serve aitchbone roast cooked below the medium well-done point.
Remove the beef from the refrigerator and pat it dry with paper towels. Cover in plastic wrap and let it warm up to room temperature for 90 minutes.
Preheat the oven to 350 F.
Combine the extra virgin olive oil or vegetable oil and unsalted butter in a small saucepan. Stir the mixture over low heat until the butter is fully melted.
Brush the olive oil and butter mixture over the entire cut of beef. Season the meat with kosher salt and freshly ground black pepper to taste.
Place the beef in a baking dish and cover with a tight-fitting lid.
Cook the beef in the oven for two hours without opening the oven door.
Check the internal temperature of the beef with a meat thermometer at the thickest point, making sure the tip isn't touching bone. When the meat is cooked to the rare point, the temperature is 120 to 125 F; medium-rare is 125 to 130 F; medium-well is 130 to 140 F; and well-done is above 145 F.
Transfer the beef to a warmed serving platter and allow it to rest for 10 minutes before serving, so the natural juices can redistribute throughout the meat.