Preheat your oven to 400°F (200°C).
Prepare the pork by slicing it lengthwise to create a pocket, being careful not to cut all the way through.
Layer the fresh basil leaves and mozzarella cheese inside the pocket of the pork tenderloin.
Close the pork and secure the opening with three or four toothpicks to keep the filling inside.
In a small bowl, mix the sea salt, black pepper, garlic powder, and dried oregano together.
Rub the spice mixture evenly over the outside of the pork tenderloin.
Chop the zucchini and red bell pepper into bite-sized pieces.
Heat 1 teaspoon of olive oil in a large oven-safe skillet over medium-high heat and sear the pork for 2 minutes per side until browned.
Remove the skillet from heat, toss the chopped vegetables with the remaining teaspoon of olive oil, and scatter them around the pork.
Place the skillet in the oven and roast for 12 to 15 minutes, or until the pork reaches an internal temperature of 145°F.
Remove from the oven and let the meat rest for 5 minutes before removing toothpicks and slicing.