Thinly slice the flank steak against the grain into bite-sized strips and season with cumin, garlic powder, sea salt, and black pepper.
De-seed the poblano pepper and slice into thin strips; thinly slice the red onion.
Heat the avocado oil in a large non-stick skillet over medium-high heat.
Add the steak strips 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, add the poblano peppers and onions, sautéing for 4-5 minutes until they are tender and slightly charred.
Wipe the skillet clean and place the whole wheat tortilla in the pan over medium heat.
Sprinkle half of the shredded cheddar cheese over one half of the tortilla, then layer on the cooked steak, sautéed peppers, onions, and fresh cilantro.
Top with the remaining cheese and fold the tortilla in half.
Cook for 2 minutes per side until the tortilla is golden brown and the cheese is completely melted.
Slice into wedges and serve immediately.