01 - Preheat a grill pan or skillet over medium-high heat. Rub the steak with olive oil, chili powder, cumin, salt, and pepper.
02 - Grill the steak for 3-4 minutes per side for medium-rare, or until desired doneness is reached. Transfer to a cutting board and rest for 5 minutes, then slice thinly against the grain.
03 - In the same pan, add the sliced bell pepper, onion, and jalapeño. Sauté until softened and lightly golden, approximately 5 minutes. Remove from heat and set aside.
04 - Lay out the flour tortillas flat. On one half of each tortilla, layer sliced steak, sautéed vegetables, and shredded cheese. Fold the tortilla in half to enclose the filling.
05 - Wipe the pan clean and return to medium heat. Cook each quesadilla 2-3 minutes per side, pressing gently with a spatula, until the tortilla is golden and the cheese has fully melted.
06 - Transfer the cooked quesadillas to a cutting board and slice each into wedges. Serve immediately with sour cream, salsa, chopped cilantro, and lime wedges.