Slice the lean sirloin steak into thin strips and season evenly with sea salt, black pepper, cumin, and garlic powder.
De-seed the poblano pepper and slice it into thin strips along with the red onion.
Heat avocado oil in a large non-stick skillet over medium-high heat.
Add the poblano peppers and onions to the skillet, sautéing for 4-5 minutes until they are softened and show slight char marks.
Push the vegetables to the outer edges of the pan and add the steak strips to the center, searing for 2-3 minutes until browned and cooked to your preference.
Remove the steak and vegetable mixture from the skillet and set aside on a plate.
Wipe the skillet clean and place the whole wheat tortilla in the pan over medium heat.
Spread half of the Monterey Jack cheese over one half of the tortilla, layer on the steak and vegetable mixture, and top with the remaining cheese.
Fold the tortilla in half and press down slightly with a spatula, cooking for 2 minutes per side until the tortilla is golden brown and the cheese is fully melted.
Transfer to a cutting board, let rest for one minute, then slice into wedges and garnish with fresh cilantro.