Remove the roast from packaging and pat it completely dry. Season generously with kosher salt and let it rest uncovered in the refrigerator if possible. This step enhances flavor and helps create a beautiful crust.
Mix olive oil, minced garlic, black pepper, and rosemary in a bowl. Rub the mixture evenly over all sides of the roast. Make sure every surface is coated for maximum flavor.
Place sliced onions at the bottom of the pan to act as a natural rack. Pour beef broth into the pan to prevent drippings from burning. This also helps create a flavorful sauce.
Preheat the oven to a high temperature to start the browning process. Place the roast in the oven, then reduce the heat and continue cooking slowly. Always use a thermometer to check internal temperature for desired doneness.
Remove the roast from the oven once it reaches the target temperature. Cover it loosely with foil and let it rest for at least 20–30 minutes. Slice against the grain for the most tender pieces.