Preheat and prep: Heat the oven to 400°F (205°C). Pat the pork dry. Mix salt, pepper, and garlic powder, then season the tenderloins all over.
Sear the pork: Heat a large oven-safe skillet over medium-high.
Add oil and 1 tablespoon butter. Sear tenderloins on all sides until golden, about 2–3 minutes per side.
Start the glaze base: Push pork to the side. Add minced garlic and cook 30 seconds until fragrant.
Carefully pour in the bourbon. Let it bubble 30–60 seconds to reduce slightly.
Build the sauce: Stir in brown sugar, soy sauce, Dijon, vinegar, and red pepper flakes. Spoon some sauce over the pork to coat.
Roast: Transfer the skillet to the oven.
Roast 12–18 minutes, turning once and basting with sauce halfway, until the thickest part reads 140–145°F (60–63°C).
Rest the meat: Move pork to a cutting board and tent with foil. Rest 8–10 minutes so the juices settle.
Reduce the glaze: Set the skillet on medium heat. Simmer the pan sauce 3–5 minutes until glossy and slightly thick.
If it reduces too much, add a splash of chicken stock or water. Whisk in the remaining 2 tablespoons butter for a silky finish.
Slice and serve: Slice pork into 1/2-inch medallions. Spoon the bourbon glaze over the top.
Garnish with chopped herbs if you like.