01 - In a mixing bowl, toss steak slices with olive oil, cumin, smoked paprika, garlic powder, salt, pepper, and lime juice. Let marinate for 10 minutes.
02 - Heat a large skillet or grill pan over medium-high heat. Sear the steak for 2 minutes per side until browned but still tender. Remove and set aside.
03 - In the same pan, sauté onion and bell pepper with jalapeño if using for 3–4 minutes until softened.
04 - Wipe the skillet clean. Place a tortilla on the skillet over medium heat. Sprinkle a quarter of the cheese over half the tortilla, then layer steak, vegetables, and cilantro. Fold the tortilla over to enclose the filling.
05 - Cook for 2–3 minutes per side, pressing lightly, until the tortilla is golden and the cheese is melted.
06 - Repeat with remaining tortillas and filling. Allow quesadillas to rest briefly before slicing. Serve hot with salsa, sour cream, and guacamole.