Slice the sirloin steak into very thin strips against the grain and thinly slice the bell pepper and onion.
In a small bowl, combine the sea salt, black pepper, chili powder, and garlic powder, then toss the steak strips in the seasoning until evenly coated.
Heat half of the olive oil in a large non-stick skillet over medium-high heat and sauté the peppers and onions until they are tender and slightly charred, then remove them from the pan.
Add the remaining olive oil to the same skillet and sear the steak strips for 2-3 minutes until browned and cooked through, then remove and set aside.
Wipe the skillet clean and place the tortilla in the pan over medium heat, sprinkling the cheese over one half of the tortilla.
Layer the cooked steak and sautéed vegetables over the cheese, then fold the tortilla in half.
Cook for 1-2 minutes per side until the tortilla is golden-brown and the cheese is completely melted.
Remove from the heat, let it rest for one minute, and slice into wedges before serving.