Preheat and prep: Set your oven to 400°F (205°C). Pat the pork tenderloin dry with paper towels. Trim any silverskin. Season all over with 1–1.5 teaspoons kosher salt and 1/2 teaspoon black pepper.

Sear the pork: Heat a large oven-safe skillet over medium-high heat. Add oil. When shimmering, sear the pork on all sides until browned, about 2–3 minutes per side. This should take 6–8 minutes total.

Roast to temp: Transfer the skillet to the oven. Roast until the thickest part reaches 140–145°F (60–63°C), about 10–15 minutes depending on size. Start checking at 10 minutes.

Rest the meat: Move the pork to a cutting board and tent loosely with foil. Rest 5–10 minutes. This keeps it juicy and lets the temperature even out.

Make the glaze: Return the skillet to the stove over medium heat. If the pan is dry, add a teaspoon of oil. Add garlic and cook 20–30 seconds until fragrant, stirring so it doesn’t burn.

Build the sauce: Stir in honey, soy sauce, and vinegar. Add Dijon and red pepper flakes if using. Simmer 2–3 minutes, scraping brown bits from the pan, until the sauce thickens to a glossy, syrupy glaze.

Finish with butter: Off heat, swirl in butter until melted and the sauce looks smooth. Taste and adjust: add a splash more vinegar for brightness or honey for sweetness. Season with a pinch of salt if needed.

Slice and glaze: Slice the tenderloin into 1/2-inch medallions. Return slices to the skillet and spoon the glaze over them, or plate and pour the sauce on top. Garnish with herbs.

Serve: Pair with roasted veggies, mashed potatoes, rice, or a crisp salad. Spoon any extra glaze over the sides.