Preheat oven to 375°F (190°C).
In a small bowl, combine minced garlic, rosemary, 2 tablespoons olive oil, salt, pepper, and onion powder to create a herb paste.
Pat the beef roast dry with paper towels and apply the herb paste uniformly across all surfaces of the meat.
Toss baby potatoes with the remaining 1 tablespoon of olive oil and a pinch of salt in a large roasting pan.
Position the beef roast in the center of the roasting pan, distributing the potatoes in a single layer around the meat.
Roast in the center of the oven for 60 to 75 minutes, or until an internal meat thermometer inserted into the thickest part reaches 135°F (57°C) for medium-rare.
Remove the roast from the oven and transfer to a carving board; tent loosely with aluminum foil and allow to rest for 15 minutes.
If potatoes require additional browning, return them to the oven while the meat rests.
Carve the beef against the grain into thin slices and serve alongside the roasted potatoes.