Preheat and prep the pan: Heat the oven to 425°F (220°C). Line a large sheet pan with parchment or foil for easy cleanup.
Lightly oil the surface.
Mix the rub: In a small bowl, combine salt, pepper, smoked paprika, garlic powder, onion powder, cumin, and cayenne (if using).
Season the pork: Pat the tenderloins dry, then rub with 1 tablespoon olive oil. Sprinkle the spice mix all over and press it in so it sticks.
Toss the vegetables: In a large bowl, combine potatoes, red onion, bell peppers, and broccoli with 1 tablespoon olive oil, minced garlic, thyme, and a good pinch of salt and pepper. Spread them on the prepared sheet pan in an even layer, leaving room in the center for the pork.
Start roasting: Roast the vegetables for 10 minutes alone to get a head start on the potatoes.
Make the glaze: In a small bowl, stir together BBQ sauce, apple cider vinegar, and honey or brown sugar (if using).
Set aside.
Add the pork: Remove the pan, push the vegetables to the edges, and place the seasoned tenderloins in the center. Return the pan to the oven and roast for 10 minutes.
Glaze and finish: Brush the pork generously with the BBQ glaze. Flip the tenderloins, brush the other side, and give the vegetables a quick toss.
Roast another 8–12 minutes, until the pork registers 140–145°F (60–63°C) at the thickest part.
Rest the meat: Transfer the tenderloins to a cutting board and tent loosely with foil. Let rest for 8–10 minutes so the juices settle. Toss the veggies on the pan with any remaining glaze and return to the oven for 3–5 minutes if you want extra caramelization.
Slice and serve: Slice the pork into 1/2-inch medallions.
Serve with the roasted vegetables and lemon wedges. Spoon any pan juices over the top for extra flavor.