Thinly slice the flank steak against the grain into bite-sized strips.
In a small bowl, toss the steak with chili powder, cumin, sea salt, and black pepper until evenly coated.
Heat 0.5 tsp of olive oil in a large skillet over medium-high heat.
Add the steak to the skillet and sear for 2-3 minutes per side until browned and cooked through; remove and set aside.
In the same skillet, add the remaining 0.5 tsp of olive oil along with sliced red bell peppers and onions, sautéing until softened and slightly charred.
Squeeze the juice of half a lime over the steak and vegetables, then stir in the fresh cilantro.
Wipe the skillet clean and place the tortilla inside over medium heat.
Sprinkle half of the Monterey Jack cheese on one side of the tortilla, top with the steak and vegetable mixture, then add the remaining cheese.
Fold the tortilla in half and cook for 2 minutes per side until the exterior is golden brown and the cheese is fully melted.
Slice into wedges and serve immediately.