Prepare the Pork Tenderloin

1. Preheat Oven: Preheat your oven to 400°F (200°C).
2. Season the Pork: In a small bowl, mix together the garlic powder, onion powder, smoked paprika, salt, and pepper. Rub this seasoning all over the pork tenderloin, making sure it’s coated evenly.
3. Sear the Pork: Heat 2 tablespoons of olive oil in a large oven-safe skillet over medium-high heat. Once the oil is hot, sear the pork tenderloin for 2-3 minutes on each side, until golden brown.
4. Add Rosemary: Sprinkle the rosemary over the pork. Transfer the skillet to the oven and roast for 25-30 minutes, or until the pork reaches an internal temperature of 145°F (63°C).

Prepare the Vegetables

1. Season the Vegetables: While the pork is roasting, toss the cubed potatoes, sliced carrots, red onion, and bell pepper with 2 tablespoons of olive oil. Season with salt and pepper.
2. Roast the Vegetables: After the pork has been in the oven for about 15 minutes, add the vegetables to the skillet around the pork. Continue roasting everything for the remaining 15-20 minutes.

Finish and Serve

1. Rest the Pork: Once the pork is done, remove it from the oven and let it rest for 5-10 minutes before slicing.
2. Serve: Slice the pork tenderloin into medallions and serve with the roasted vegetables.