Slice the sirloin steak into thin, bite-sized strips against the grain for maximum tenderness.
In a small bowl, combine the sea salt, black pepper, ground cumin, and garlic powder, then toss with the steak strips to coat evenly.
Thinly slice the bell pepper and red onion into uniform strips.
Heat the avocado oil in a large skillet over medium-high heat until it begins to shimmer.
Add the seasoned steak to the skillet and sear for 2-3 minutes until browned and cooked through, then remove from the pan and set aside.
In the same skillet, sauté the bell peppers and onions for 4-5 minutes until they are tender-crisp and slightly caramelized.
Wipe the skillet clean and return it to medium heat.
Place the sprouted grain tortilla in the skillet, sprinkle half of the cheddar cheese over one side, then top with the steak and sautéed vegetables.
Sprinkle the remaining cheese over the filling and fold the tortilla in half to close.
Cook for approximately 2 minutes per side until the tortilla is golden brown and the cheese is completely melted.