Rub the oil and a generous amount of salt onto the beef. Season with garlic powder, onion powder, and black pepper. Place the beef on a foil lined baking sheet and let it sit out on the counter for 30 to 45 minutes before cooking to come to room temperature, this will help the roast cook evenly.
Preheat the oven to 300°F.
Preheat a cast iron skillet or wide pot on medium high heat. When the pan is hot, sear all sides of the beef for 1 minute each until nicely browned.
Place the beef back on the foil-lined baking sheet and cook in the oven for about 13 to 15 minutes per pound for rare roast beef until the internal temperature reaches 115°F using a thermometer. (Periodically check the temperature with a thermometer throughout cooking to achieve the desired temperature.) Cook longer if you desire a more done roast. (See below.)
Once the desired temperature is achieved, let the roast rest on a cutting board until fully cooled before slicing (about 30 minutes depending upon the size).
Very thinly slice against the grain. Only slice what you need to use, wrap the rest tightly and refrigerate. Will stay good for 5 to 7 days refrigerated.