In a bowl, mix the sliced flank steak with smoked paprika, cumin, salt, and pepper. Let it marinate for at least 15 minutes to enhance the flavors.
In a large skillet, melt 2 tablespoons of butter over medium-high heat. Add the marinated steak and cook for about 3-4 minutes until it is browned and cooked through. Add minced garlic to the skillet during the last minute of cooking. Remove from heat and set aside.
In the same skillet, reduce the heat to medium. Place one flour tortilla in the skillet and top with a generous portion of the cooked steak, followed by a mix of pepper jack and cheddar cheese.
Place another tortilla on top and press down gently. Cook for about 2-3 minutes or until the bottom tortilla is golden and crispy.
Carefully flip the quesadilla using a spatula. Add the remaining 2 tablespoons of butter around the edges of the quesadilla, allowing it to seep in as it cooks. Cook for another 2-3 minutes until the cheese is melted and the tortilla is golden brown.
Remove the quesadilla from the skillet and let it rest for a minute before slicing it into wedges. Garnish with chopped cilantro.
Serve the quesadillas warm with sour cream and salsa on the side for dipping.
Notes
Let the steak marinate for at least 15 minutes for better flavor.