In a small bowl, combine the chopped rosemary, thyme, minced garlic, olive oil, apple cider vinegar, onion powder, and smoked paprika. Stir well to create a herbaceous marinade.
Pat the pork tenderloin dry with paper towels. Season the pork generously with sea salt and freshly ground black pepper (or white pepper if on strict AIP).
Rub the herb marinade all over the pork tenderloin, ensuring it is well-coated. Place the tenderloin in a resealable plastic bag or covered dish and marinate in the refrigerator for at least 1 hour, or overnight for deeper flavor and tenderness.
Preheat your oven to 375°F (190°C).
Remove the pork tenderloin from the marinade and place it on a baking sheet or in a roasting pan. Roast in the preheated oven for 25-30 minutes, or until the internal temperature reaches 145°F (63°C) and the meat is tender and juicy.
Remove the pork tenderloin from the oven and let it rest for 5-10 minutes before slicing. This allows the juices to redistribute and keeps the meat moist.
Slice the pork tenderloin into medallions and serve warm.