Prep the oven and pan: Preheat the oven to 400°F (205°C). Line a sheet pan with foil and place a wire rack on top for extra crispness, or simply use a lightly oiled sheet pan.

Trim the tenderloin: Pat the pork dry with paper towels. Use a sharp knife to remove any silver skin so the crust adheres well and the meat stays tender.

Season the meat: Sprinkle the tenderloin all over with a pinch of kosher salt and black pepper. Let it sit for 5 minutes while you make the coating.

Mix the crust: In a shallow bowl, combine Parmesan, panko, Italian seasoning, garlic powder, onion powder, paprika, 1/2 teaspoon salt, and pepper. Stir well so the seasoning is even.

Make the binder: In a small bowl, whisk Dijon mustard with 1 tablespoon olive oil. For extra insurance, whisk in the beaten egg. This helps the crust cling tightly and creates a richer crust.

Coat the pork: Brush the mustard mixture over the entire tenderloin. Press the Parmesan mixture onto all sides, gently but firmly, to create an even crust. Transfer to the prepared rack or pan.

Quick sear for color (optional but recommended): Heat a tablespoon of oil in an oven-safe skillet over medium-high. Sear the crusted pork for 45–60 seconds per side until lightly golden, then move the skillet to the oven. If skipping the sear, just bake on the sheet pan.

Bake: Roast for 15–20 minutes, depending on thickness, until the center reaches 140–145°F (60–63°C) on an instant-read thermometer. The crust will turn golden and crisp.

Rest: Remove from the oven and let the pork rest for 5–10 minutes. Resting keeps the juices inside and the slices tender.

Slice and serve: Cut into 1/2-inch medallions. Sprinkle with chopped herbs and a squeeze of lemon if you like. Serve with your favorite sides.