Slice the flank steak into very thin strips against the grain to ensure a tender bite.
In a small bowl, mix the chili powder, ground cumin, garlic powder, sea salt, and black pepper.
Toss the steak strips in the spice blend until they are thoroughly and evenly coated.
Heat half of the olive oil in a non-stick skillet over medium-high heat and sauté the sliced bell peppers and onions until softened.
Remove the vegetables from the pan, add the remaining oil, and sear the steak strips for 2-3 minutes until browned.
Wipe the skillet clean and place the tortilla in the pan over medium heat.
Sprinkle half of the cheese on one side of the tortilla, then layer on the steak and vegetables, followed by the remaining cheese.
Fold the tortilla over and cook for 2 minutes per side until the exterior is golden-brown and the cheese is fully melted.
Squeeze the fresh lime juice over the steak filling before serving for a bright, citrusy finish.