Preheat and prep. Set your oven to 400°F (200°C). Pat the pork tenderloin dry with paper towels. Trim any silver skin if not already removed for better texture.

Season generously. Mix 1 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon onion powder, and 1/2 teaspoon smoked paprika. Rub it all over the pork. Let it sit at room temp for 10–15 minutes while you prep the garlic butter.

Make the garlic butter. In a small bowl, combine 3 tablespoons softened butter, minced garlic, 1 tablespoon chopped fresh thyme, 1 tablespoon chopped parsley, lemon zest, and a pinch of red pepper flakes if using. Stir until smooth.

Sear the pork. Heat a large oven-safe skillet (cast iron is ideal) over medium-high heat. Add the oil and 1 tablespoon butter. When hot and foamy, sear the pork on all sides until browned, about 2–3 minutes per side.

Add flavor before roasting. Turn off the heat. Spread half of the garlic butter across the top and sides of the tenderloin. Pour the broth or wine into the skillet around the meat, not over it.

Roast to perfect doneness. Transfer the skillet to the oven. Roast 10–15 minutes, or until the thickest part reaches 140–145°F (60–63°C) on an instant-read thermometer. Time will vary with thickness.

Rest the meat. Move the pork to a cutting board and tent loosely with foil for 5–10 minutes. This helps the juices redistribute and keeps it tender.

Finish the pan sauce. Place the skillet back on low heat. Whisk in the remaining garlic butter and a squeeze of lemon juice. Simmer 1–2 minutes until glossy. Taste and adjust salt and pepper.

Slice and serve. Cut the pork into 1/2-inch medallions. Spoon the garlic butter pan sauce over the top. Sprinkle with extra herbs if you like.