Warm the pork with sauce. In a skillet over medium heat, combine pulled pork with the BBQ sauce.
Stir until heated through and glossy, 3–5 minutes. Taste and adjust with more sauce, salt, or a splash of apple cider vinegar if you want extra tang.
Prep fillings. Shred the cheese and slice the onion. Pat the pork slightly dry if it’s very saucy; you want it moist, not dripping, so the tortillas stay crisp.
Heat the skillet. Wipe the skillet clean, then add a light coating of butter or oil over medium heat.
You want steady heat for an even, golden crust.
Assemble the first quesadilla. Place a tortilla in the skillet. Sprinkle a thin layer of cheese over half the tortilla, add a layer of pork, scatter onions and jalapeños, and finish with another light layer of cheese. Fold the tortilla over to close.
Cook until crisp. Press gently with a spatula.
Cook 2–3 minutes per side, flipping once, until the tortilla is browned and the cheese is melted. Adjust heat so it browns without burning.
Repeat. Transfer to a cutting board and let rest for 1 minute. Cook remaining quesadillas, adding more butter or oil as needed.
Garnish and serve. Slice into wedges.
Top with chopped cilantro and a squeeze of lime. Serve with sour cream, extra BBQ sauce, salsa, or a simple slaw on the side.