Preheat the oven to 400°F (200°C) and pat the pork tenderloin dry with paper towels.
Season the pork all over with black pepper, smoked paprika, garlic powder, and onion powder.
Now, to sear the pork: Start by heating the olive oil in a large oven-safe skillet over medium-high heat. Add the tenderloin and sear for 2–3 minutes per side, until browned all over. Remove the skillet from heat.
To make the glaze: Whisk together the Coca-Cola, barbecue sauce, soy sauce, Dijon mustard, apple cider vinegar, and chili flakes (if using) in a small bowl.
Pour half the glaze over the pork in the skillet, then transfer the skillet to the oven and roast for 18–22 minutes, or until the internal temperature reaches 145°F (63°C).
Remove pork from the skillet and let it rest for 5–10 minutes. Meanwhile, place the skillet back on the stove over medium heat. Add the remaining glaze and let it simmer for 3–5 minutes until thickened.
Slice the tenderloin into medallions, then drizzle it with the reduced glaze. Make sure to serve it hot.
