1. Heat oven to 425 degrees F. Combine rosemary, garlic, salt, and pepper; press 1 1/2 teaspoons of the mix evenly onto beef. Stir oil into remaining seasoning mixture and set aside.
2. Toss potatoes, carrots, onions, and remaining seasoning mixture to coat. Arrange in a single layer on metal baking sheet. Set aside.
3. Place beef on rack in shallow baking pan. Place both beef and vegetables in oven and roast until halfway cooked (25 minutes).
4. Stir vegetables and add zucchini to baking pan. Continue roasting until vegetables are tender and meat reaches a minimum internal temperature of 145 degrees F (20-25 minutes).
5. Turn oven off, but leave vegetables inside to remain warm while beef rests. Transfer beef to carving board, tent with foil, and let rest (15 minutes).
6. Carve beef into slices. Serve with vegetables.