Slice the flank steak against the grain into thin, bite-sized strips.
In a small bowl, whisk together 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 skillet over medium-high heat until shimmering.
Add the steak to the skillet and sear for 3-4 minutes until browned and caramelized, then remove and set aside.
In the same skillet, sauté the thinly sliced bell peppers and onions for 3 minutes until tender and slightly charred.
Wipe the skillet clean and place the tortilla in the pan over medium heat.
Sprinkle half the cheese on one side of the tortilla, then layer on the cooked steak, sautéed veggies, and the remaining cheese.
Squeeze the fresh lime juice over the filling and fold the tortilla in half.
Cook for 2-3 minutes per side until the tortilla is golden brown and the cheese is fully melted.