Thinly slice the flank steak against the grain into bite-sized strips.
In a small bowl, whisk together the lime juice, chili powder, cumin, garlic powder, sea salt, and black pepper.
Toss the steak strips in the marinade until evenly coated.
Heat the olive oil in a large skillet over medium-high heat.
Add the bell peppers and red onion, sautéing until they are tender and slightly charred.
Push the vegetables to the side and add the steak, searing for 3-4 minutes until browned and cooked through.
Remove the steak and vegetables from the skillet and wipe it clean.
Place the tortilla in the skillet over medium heat and sprinkle half of the cheddar cheese on one half.
Layer the steak and vegetable mixture over the cheese, then top with the remaining cheese.
Fold the tortilla over and cook for 2 minutes per side until the exterior is golden and the cheese is melted.