Place the beef on parchment paper or a cutting board and sprinkle all sides with kosher salt.
Wrap the beef in plastic wrap and place it in the refrigerator overnight (or ideally up to 24 hours).
Remove the plastic wrap and pat the beef dry with a paper towel. Allow it to sit at room temperature for 30 minutes.
Preheat the oven to 250 degrees F.
In a small bowl, combine the rosemary, thyme, pepper, and garlic powder. Set aside.
Place the beef on parchment paper or plastic wrap, brush all sides with olive oil, and then sprinkle the herb mixture evenly over the meat, pressing gently to help it adhere.
Place the beef (fat side up) on a wire rack set into a baking sheet.
After 1 hour and 40 minutes of cooking, check the internal temperature of the roast by poking the thermometer into the thickest part. It should have an internal temperature of 120 degrees F. If not, continue cooking, checking every 10 minutes or so.
Once the roast has reached 120 degrees F, turn off the oven and keep the door closed. Let the roast cook for a further while (about 45 minutes more) or until it reaches an internal temperature of 135 degrees F for medium-rare.
Remove the roast from the oven and transfer it to a cutting board. Loosely tent it with foil and let it rest for 20 minutes.
Cut the roast into thin slices against the grain and serve.