Prepare the Pan: Coat a shallow roasting pan with nonstick cooking spray.
Arrange: Place the pork tenderloins in the center of the pan. Arrange the quartered potatoes, carrots, and onion wedges around the meat.
Season: Drizzle the olive oil over the ingredients. Combine the rosemary, salt, and pepper in a small bowl, then sprinkle the mixture evenly over the meat and vegetables.
Roast: Bake, uncovered, at 450°F for 30–40 minutes. Stir the vegetables occasionally during cooking to ensure even browning.
Finish: The dish is ready when a meat thermometer reads 160°F.