Juicy pork tenderloin with a brown sugar garlic rub, seared in a skillet, roasted at 400°F, and brushed with barbecue sauce at the end for a glossy, caramelized glaze.
Pat the pork tenderloin dry with paper towels and trim away any silver skin.
In a small bowl, mix the brown sugar, garlic powder, onion powder, paprika, salt, and pepper. Rub the pork all over with the oil, then coat it evenly with the seasoning mixture.
Heat an oven-safe skillet over medium-high heat. Sear the pork 2 to 3 minutes per side, turning until browned on most sides. If the brown sugar starts getting too dark, reduce the heat.
Transfer the skillet to the oven and roast about 10 to 14 minutes.
Brush the pork with BBQ sauce and return it to the oven for another 3 to 5 minutes, until the thickest part reaches 145°F on an instant-read thermometer.
Optional: for a stickier glaze, brush on a little more BBQ sauce and broil 1 to 2 minutes, watching closely so it does not burn.
Let the pork rest 5 to 10 minutes before slicing. Optional: while the pork rests, add the butter to the warm skillet and swirl it into the pan drippings until melted. If the drippings look scorched, skip this and wipe the pan.
Slice into medallions, spoon the buttery pan drippings over the top if you made them, and serve with extra warm BBQ sauce on the side.
Notes
Add the BBQ sauce in the last 3 to 5 minutes so it glazes instead of burning. For a richer finish, swirl the optional tablespoon of butter into the pan drippings after the pork comes out and spoon it over the sliced medallions. Leftovers keep in an airtight container in the refrigerator for 3 to 4 days.