Slice the flank steak into very thin strips against the grain to ensure tenderness.
In a medium bowl, whisk together the chili powder, cumin, garlic powder, sea salt, black pepper, and the juice of the half lime.
Toss the steak strips in the spice mixture until evenly coated and let marinate for 10 minutes.
Heat 0.5 tsp of olive oil in a large non-stick skillet over medium-high heat.
Add the sliced bell peppers and red onion to the skillet, sautéing for 4-5 minutes until they are tender-crisp and show slight char marks.
Remove the vegetables from the skillet and set aside on a plate.
Add the remaining 0.5 tsp of olive oil to the same skillet and sear the steak strips for 2-3 minutes, stirring occasionally, until browned and cooked through.
Wipe the skillet clean and return it to medium heat, then place the whole wheat tortilla in the pan.
Sprinkle half of the shredded cheddar cheese onto one half of the tortilla.
Layer the cooked steak, sautéed peppers, and onions over the cheese, then top with the remaining cheese.
Fold the tortilla in half and press down gently with a spatula.
Cook for 2 minutes per side until the tortilla is golden brown and the cheese has completely melted.
Remove from the pan, garnish with freshly chopped cilantro, and slice into three wedges before serving.