Preheat the oven to 350 degrees F. Line a large baking pan with aluminum foil. Grease the foil with oil or cooking spray.
Place the tenderloins in the center of the prepared pan and set aside.
Combine the 1/2 cup oil with the vinegar, honey, garlic, onion, rosemary, salt and pepper in a large bowl. Whisk to combine. Reserve 2/3 cup of the marinade in a small saucepan. Stir the potatoes and carrots into the large bowl. Toss to combine.
Drizzle 1/3 cup of the reserved marinade over the pork, coating all the sides. Set the remaining 1/3 cup marinade aside to serve as a sauce. Scatter the potatoes and carrots evenly around the pork. Roast in the oven until the pork reaches an internal temperature of 145 degrees F, about 50 minutes. Let the pork rest for 5 to 10 minutes before slicing.
While the pork is resting, heat the remaining marinade in the small saucepan.
Slice the pork and drizzle with the warm marinade.