Step 1: Prepare your steak. Thinly slice 1 lb of flank steak or sirloin against the grain into small, bite-sized pieces. In a medium bowl, toss the steak with 1 tbsp olive oil, 1 tsp chili powder, 1/2 tsp cumin, 1/2 tsp smoked paprika, 1/4 tsp garlic powder, and salt and black pepper to taste. Ensure the steak is evenly coated.
Step 2: Cook the steak. Heat a large skillet (cast iron works wonderfully) over medium-high heat. Once hot, add the seasoned steak in a single layer, ensuring not to overcrowd the pan. Cook for 2-3 minutes per side, or until beautifully browned and cooked to your desired doneness. Remove the steak from the skillet and set aside. Don’t clean the skillet yet; those flavorful bits will enhance your quesadilla!
Step 3: Assemble the quesadillas. Reduce the heat to medium. Place one large flour tortilla in the hot skillet. Sprinkle half of one side of the tortilla with a generous amount of shredded cheese (about 1/4 cup).
Step 4: Add fillings. Over the cheese, spread a portion of the cooked steak, some finely diced red onion (if using), and a sprinkle of chopped fresh cilantro (if using). Add another layer of cheese over the steak and toppings.
Step 5: Fold and cook. Fold the empty half of the tortilla over the filled half, creating a crescent shape. Cook for 2-3 minutes per side, or until the tortilla is golden brown and crispy, and the cheese is completely melted and gooey. Press down gently with a spatula to ensure even cooking and melting.
Step 6: Repeat and serve. Transfer the cooked quesadilla to a cutting board. Repeat with the remaining tortillas and fillings. Cut each quesadilla into wedges. Serve immediately with your favorite accompaniments like salsa, sour cream, and guacamole.