01 - Set oven to 425°F and line a baking sheet with parchment paper.
02 - Toss diced sweet potatoes, sliced red onion, and diced bell pepper with olive oil, salt, and pepper in a large bowl; spread evenly on the baking sheet.
03 - Roast vegetables for 20 to 25 minutes, stirring once halfway through, until tender and caramelized.
04 - In a mixing bowl, combine roasted vegetables, black beans, shredded cheese, cilantro if using, cumin, smoked paprika, and chili powder; mix gently.
05 - Lay out tortillas, spread one-quarter of the filling over half of each tortilla, then fold to close.
06 - Heat a large non-stick skillet over medium heat and lightly grease with oil or cooking spray. Cook two quesadillas at a time for 2 to 3 minutes per side until golden and cheese melts.
07 - Slice into wedges and serve immediately with salsa, sour cream, or guacamole as desired.