Slice the flank steak into thin strips against the grain for maximum tenderness.
In a small bowl, whisk together the lime juice, chili powder, cumin, sea salt, and black pepper to create a marinade.
Toss the steak strips in the marinade until evenly coated.
Heat half of the avocado oil in a large skillet over medium-high heat.
Add the sliced bell peppers and onions, sautéing until they are softened and slightly charred.
Remove the vegetables from the skillet and set aside.
Add the remaining avocado oil to the same skillet and sear the steak strips for 2-3 minutes until browned and cooked through.
Wipe the skillet clean and place the sprouted grain tortilla in the pan over medium heat.
Layer half the cheddar cheese on one side of the tortilla, top with the steak and vegetable mixture, and finish with the remaining cheese.
Fold the tortilla in half and cook for 2-3 minutes per side until the cheese is melted and the exterior is golden and crispy.