Prep the backstrap: Trim off any silver skin. Pat dry thoroughly for better browning.
Marinate (20–30 min): In a bowl, whisk olive oil, lemon juice, garlic, Dijon, salt, pepper, smoked paprika, rosemary, and thyme. Coat the backstrap; rest at room temp 20–30 minutes (or refrigerate up to 4 hours, then bring to room temp).
Preheat: Set oven to 400°F (200°C). Place a large oven-safe skillet over medium-high heat until very hot.
Sear: Shake excess marinade from the meat. Add a light film of oil to the hot pan if needed. Sear 2–3 minutes per side until a deep brown crust forms; quickly sear the edges.
Roast: Transfer skillet to oven and roast 5–10 minutes, depending on thickness, until internal temp reaches 140–145°F (60–63°C) for juicy, safe doneness.
Rest & make pan sauce: Move backstrap to a plate; tent loosely with foil. Return skillet to medium heat; add butter and stock, scraping browned bits. Simmer 1–2 minutes. Pour in any resting juices.
Slice & serve: Slice across the grain into ½-inch (1–1.5 cm) medallions. Spoon pan sauce over the top. Garnish with parsley, lemon zest, and a pinch of flaky salt.
