Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Pat the pork tenderloin dry with a paper towel and rub with olive oil, then season evenly with sea salt, black pepper, and dried rosemary.
Trim the ends off the Brussels sprouts and cut them in half, tossing them lightly with a pinch of salt and pepper.
Place the seasoned pork tenderloin and the Brussels sprouts onto the prepared baking sheet, ensuring the sprouts are in a single layer.
Roast in the oven for 18 to 22 minutes, or until the pork reaches an internal temperature of 145°F and the sprouts are tender and charred.
While the pork roasts, core and slice the Fuji apple into thin wedges.
Heat the ghee in a small skillet over medium heat, add the apple slices, and sprinkle with ground cinnamon.
Sauté the apples for 5 to 7 minutes until they are soft, golden, and caramelized.
Remove the pork from the oven and let it rest for 5 minutes before slicing into medallions.
Plate the sliced pork topped with the caramelized apples and serve alongside the roasted Brussels sprouts.