Pat dry and trim: Pat the pork tenderloin dry with paper towels. If needed, remove the silver skin with a sharp knife. Dry meat browns better and helps the rub stick.

Mix the rub: In a small bowl, combine salt, pepper, brown sugar, smoked paprika, garlic powder, onion powder, ground mustard, and cayenne (if using).

Season generously: Rub 1 tablespoon of oil over the pork. Sprinkle the spice mix all over, pressing it into the surface so it clings well.

Preheat your cooking method: Grill: Heat to medium-high (about 400–425°F). Clean and oil the grates.

Skillet: Heat a large cast-iron skillet over medium-high until very hot. Add 1 tablespoon oil.

Oven: Preheat to 425°F. Preheat an oven-safe skillet or sheet pan inside for better sear.

Sear for crust: Place the pork on the hot grill or skillet. Sear 2–3 minutes per side until browned. If baking, sear in the hot skillet first, then transfer to the oven.

Cook to temp: Continue cooking, turning every 2–3 minutes, until the thickest part reaches 135–140°F on an instant-read thermometer. This usually takes 10–15 minutes total, depending on thickness and method.

Glaze with BBQ sauce: Stir BBQ sauce with apple cider vinegar (and Dijon if using instead of ground mustard). Brush it all over the pork during the last 3–4 minutes of cooking, letting it caramelize but not burn. Aim to pull the pork at 140–145°F.

Rest before slicing: Transfer to a cutting board and rest 5–8 minutes. The temperature will rise slightly, and the juices will redistribute.

Slice and serve: Cut into 1/2-inch medallions. Serve with extra warm BBQ sauce, grilled corn, slaw, or roasted potatoes.