Place the beef strips in a large bowl or resealable plastic bag. In a blender or food processor, combine the onion, garlic, chipotle chile, adobo sauce, chile powder, cumin, oregano, olive oil, salt, pepper, and water. Blend until smooth. Pour the marinade over the meat and stir or seal the bag and massage the bag to thoroughly coat and combine. Marinate at room temperature for 30 minutes or cover and refrigerate for up to 24 hours.
Using tongs, remove the beef strips from the bag and lay them flat in the air fryer basket, minimizing overlap as much as possible; discard the marinade. Set the air fryer to 400°F for 8 minutes, turnings the beef strips halfway through the cooking time. You may have to do this in two batches.
FOR THE OVEN
Place the steak on a sheet pan in a single layer.
Set the oven to broil and cook the steak for 3-4 minutes.
Flip and allow to cook for an additional 2 minutes.
FINISHING
Divide the meat among the tortillas. Top with cheese and salsa.
Note: Nutrition facts do not include optional topping serving suggestions