Bake the onion rings according to package instructions.
Thinly slice the red onion.
Cut the pork tenderloin into medallions about 1 – 1½ inches thick.
Heat a large skillet over medium-high heat. Cook pork medallions for 2-3 minutes on each side, or until internal temperature reaches 145F. Repeat in batches if necessary.
Assemble sandwich in the following order: Martin’s Sandwich Potato Rolls, 1-2 slices pork tenderloin, Monterey Jack cheese, 2-3 thin slices red onion, 1-2 onion rings, and BBQ sauce of choice.