Rub exterior with olive oil and then season roast generously with kosher salt and freshly ground black pepper. This is best done if you can several days in advance and then stashed away in the fridge covered with a dish towel.

On the day of cooking remove several hours early so that it can get to room temperature before cooking

Pre heat oven to 300/275. Roast fat side up for 15 minutes per pound (18 minutes if 275).

Remove from oven once an internal temperature of 110 for medium rare. The internal temperature will rise to 120-125 while resting.

Cover loosely with an aluminum foil tent, let stand for 15 minutes, though you can keep it rested like this for up to 45 minutes if you are waiting for other components of the meal to come together. The point is that this reverse sear gives you the control to finish the meat and serve when you want to.

Raise temperature to 475 degrees and cook for 20 minutes . (internal temp will end up at 135 and the exterior will be well seared)

Serve immediately, no need to rest the meat with this reverse sear.