Marinate the sliced flank steak with olive oil, garlic powder, cumin, salt, and pepper for at least 10 minutes.
Heat a skillet over medium-high heat.
Cook the flank steak for about 3-4 minutes until browned and cooked through.
Remove the steak and set aside.
In the same skillet, add sliced bell pepper and onion. Sauté until soft, about 5 minutes.
Place one tortilla in the skillet and sprinkle half with cheese.
Layer the cooked steak and sautéed vegetables over the cheese.
Add more cheese on top, then fold the tortilla in half.
Cook for 2-3 minutes until the bottom is golden brown, then flip and cook the other side.
Repeat with remaining tortillas and fillings.