Preheat your oven to 425°F (220°C) and line a sheet pan with parchment paper or lightly grease it.
Trim any excess fat from the pork tenderloin and pat dry with paper towels.
Cut the apple into wedges, peel and slice the carrot, peel (if desired) and cube the parsnip, and chop the red onion into large chunks.
Place the pork tenderloin in the center of the sheet pan. Arrange the apple, carrot, parsnip, and red onion around the pork.
Drizzle the olive oil over the pork and vegetables. Season everything with salt, pepper, and your favorite herbs such as rosemary or thyme.
Toss the vegetables lightly to coat them evenly in the oil and seasonings, ensuring the flavors meld together.
Roast in the preheated oven for about 25-30 minutes, or until the pork reaches an internal temperature of 145°F and the vegetables are tender and caramelized.
Remove from the oven and let the pork rest for 5 minutes before slicing. Serve slices of tender pork alongside the roasted fruits and vegetables.