Pull the tenderloin from the fridge 30 minutes before cooking to take the chill off. Trim away the silver skin — the thin, shiny membrane along the surface — with a sharp knife; it won't soften during cooking and will toughen the meat. Season all sides generously with kosher salt and black pepper, then rub with olive oil and any dry herbs or spices you like. If marinating, 30 min–1 hour at room temp works; for deeper flavor, refrigerate 2–12 hours then bring to room temp before roasting. Preheat oven to 425°F.

Preheat oven to 425°F. Place seasoned tenderloin in a shallow roasting pan, rack-fitted pan, or oven-safe skillet. Optional sear: heat oil over medium-high until shimmering, cook pork undisturbed 5 minutes until golden, flip and cook 3 more minutes, then move the skillet straight to the oven. Roast at 425°F for 20–30 minutes total. Seared pork may finish closer to 15–20 minutes in the oven; unseared may need 25–30. At the 20-minute mark, check internal temp at the thickest part — you're looking for 145°F. A slightly pink center at that temp is safe per USDA guidelines. If basting, do it once at the halfway point.

At 145°F internal temp, pull the pork from the oven immediately. Transfer to a cutting board and rest uncovered for 5–10 minutes — temp will rise another 5–10°F and juices will redistribute. Don't skip the rest or cut it early. Slice into 1-inch rounds and spoon pan juices or sauce over the top. Avoid: pulling before checking temp, overcooking past 160°F, or cutting before resting.