Cut the fish into four equal pieces and rub with lemon juice, salt, and pepper. Let the fish rest for 5 minutes.
Grind the tortilla chips very fine in the food processor and transfer the ground tortilla chips to a plate. Beat the egg in a deep dish.
Dip the pieces of fish into the egg one by one and roll the pieces of fish through the ground tortilla chips so that they are completely covered.
Scrub the potatoes clean and cut them lengthwise into thin strips. Soak the potato strips in water for at least 30 minutes. Drain them thoroughly and then pat them dry with kitchen paper. Coat them with oil in a boil.
Insert the separator in the AirFryer basket. Position the potato strips on one side and the pieces of fish on the other.
Slide the basket into the AirFryer. Set the timer to 12 minutes and fry the potatoes and the fish until they are crispy brown.