Slice the flank steak against the grain into very thin strips to ensure maximum tenderness.
In a small bowl, combine the chili powder, cumin, garlic powder, sea salt, and black pepper.
Toss the steak strips in the spice blend until every piece is evenly coated.
Heat the olive oil in a large non-stick skillet over medium-high heat until shimmering.
Add the sliced red bell pepper and red onion to the skillet, sautéing for 3-4 minutes until softened and slightly charred.
Move the vegetables to the side of the pan and add the steak, searing for 2 minutes until browned and cooked through.
Stir in the fresh lime juice to deglaze the pan and coat the steak, then remove the steak and vegetable mixture from the heat.
Wipe the skillet clean and place the tortilla in the pan over medium heat.
Sprinkle the shredded cheddar cheese over one half of the tortilla, top with the steak and pepper mixture, and fold the tortilla in half.
Cook for approximately 2 minutes per side until the tortilla is golden and crispy and the cheese has fully melted.