Press canned tuna in a fine-mesh strainer or cheesecloth to remove excess moisture, preventing soggy bread and ensuring better cheese adhesion and melting.

Lightly brush softened butter on the outside of your bread before air frying to achieve a golden, crispy exterior while keeping the interior tender.

Mince celery and onion into small pieces rather than chunking them, so they distribute evenly in the tuna mixture and won't create hard pockets in your sandwich.

Place a thin layer of cheddar on the bread first, then the tuna mixture, then more cheese on top to create a seal that prevents filling from leaking during air frying.

Preheat your air fryer to 375°F for 3 minutes and cook sandwiches for only 5-7 minutes, checking at the 5-minute mark to prevent over-browning while cheese melts perfectly.