Make Tuna Filling: Drain the oil or water from the tuna. Add drained tuna to a bowl and gently break up large chunks.

Add mayonnaise, celery, relish or pickles, red onion, mustard, parsley, salt, pepper and/or optional dill, hot sauce, and lemon juice. Gently stir everything together.

Assemble Sandwich: Place a slice of cheese on bread, then add some tuna and spread over the cheese. Optional: add tomato and/or pickles.

Top with another slice of cheese and bread. Spread a layer of butter on the outside of the bread.

Air Fry at 360°F/182°C for about 3-5 minutes for the cheese to melt. Carefully flip the sandwich.

Increase heat to 380°F/193°C. Air fry at 380°F/193°C for about 5 minutes or until the sandwich is to your preferred texture.

Check on the sandwich often to make sure it doesn't burn. Let the sandwich cool a bit. Cut in half if desired and enjoy asap!