Slice the flank steak into very thin strips against the grain.
In a small bowl, toss the steak strips with chili powder, sea salt, black pepper, and lime juice until evenly coated.
Heat the avocado oil in a large non-stick skillet over medium-high heat.
Add the sliced bell peppers and onions to the skillet, sautéing for 3-4 minutes until they are tender-crisp and slightly charred.
Push the vegetables to the side or remove them, then add the steak strips to the hot skillet in a single layer.
Sear the steak for 2 minutes per side until browned and cooked through, then mix with the vegetables.
Wipe the skillet clean and place the sprouted grain tortilla in the pan over medium heat.
Sprinkle the cheddar cheese over half of the tortilla, then layer the steak and vegetable mixture on top.
Fold the tortilla in half and press down firmly with a spatula.
Cook for 2 minutes per side until the exterior is golden and the cheese has fully melted.
Remove from the heat, slice into wedges, and garnish with fresh cilantro before serving.