Start by slicing the red bell pepper, green bell pepper, red onion, and jalapeños.
In a large mixing bowl, combine the sliced veggies with chili powder, sea salt, black pepper, smoked paprika, onion powder, garlic powder, ground cumin, and cayenne pepper (if using). Toss well to ensure everything is evenly coated.
Heat a skillet over medium heat. Add a splash of oil, then sauté the seasoned veggies until they are tender and slightly caramelized, about 5-7 minutes. Remove from the skillet and set aside.
In the same skillet, add your marinated flank steak. Cook it to your desired level of doneness, about 4-5 minutes per side for medium-rare. Once cooked, let it rest for a few minutes, then slice it against the grain.
Lay out a flour tortilla on a clean surface. Start layering with a generous amount of shredded Monterey Jack cheese, followed by the sautéed veggies, sliced flank steak, and a sprinkle of queso blanco. Top with another tortilla.
Return the assembled quesadilla to the skillet over medium heat. Cook until the bottom is golden and crispy, about 3-4 minutes, then carefully flip and cook the other side until equally crispy and the cheese is melted.
Once cooked, remove from the skillet and cut into wedges. Serve with a side of sour cream or Mexican crema and drizzle with chipotle vinaigrette for an extra kick.
