Preheat your oven to 400°F.
Slice the red bell pepper, yellow bell pepper, and red onion into thin, even strips.
Season the pork tenderloin on all sides with sea salt, black pepper, garlic powder, and dried oregano.
Heat the extra virgin olive oil in a large oven-safe skillet over medium-high heat.
Add the peppers and onions to the skillet and sauté for 8-10 minutes, stirring occasionally, until they are soft and deeply caramelized.
Remove the caramelized vegetables from the skillet and set them aside on a plate.
In the same skillet, sear the pork tenderloin for 2-3 minutes per side until a golden-brown crust forms.
Place the caramelized vegetables back into the skillet, arranging them around the pork.
Transfer the skillet to the oven and roast for 12-15 minutes, or until the internal temperature of the pork reaches 145°F.
Place the slices of fresh mozzarella on top of the pork tenderloin and return to the oven for 1-2 minutes until the cheese is melted and bubbly.
Remove from the oven and let the pork rest for 5 minutes before slicing into medallions.
Garnish with fresh basil leaves and serve immediately alongside the caramelized vegetables.