Pre-heat Air Fryer at 370°F (188°C). Set at 10 minutes.
In a large shallow bowl, combine mayonnaise, lemon juice, garlic powder, ground mustard seed, dill weed, cayenne (if using), kosher salt, and ground black pepper. Mix well.
In the same bowl, add tuna, celery, red onion, and sweet pickle relish. Mix well.
Mix in freshly grated mozzarella cheese. Toss gently. Set aside.
Place two slices of bread onto the Air Fryer tray. Spread softened butter on both sides. Then slowly insert tray into the middle cooking chamber, near the rotisserie catch. Air Fry for 2 minutes on each side. Remove from the cooking chamber.
See tips or notes when closing the door.
Spoon a generous amount of tuna salad over toasted bread slices and top with cheese slices. Cover with 1 slice of bread on each. Spread softened butter on each bread.
Return Air Fryer tray into the middle cooking chamber, near the rotisserie catch. Air Fry until top bread slices are crisp and golden, about 3 to 5 minutes.
Notes
This Air Fryer recipe was tested using an Instant Vortex Plus Air Fryer Oven. Not all Air Fryers cook the same way. It’s best to keep watch during your initial tests after purchasing.If you do not close the door while spreading Tuna Salad over the toasted bread, the Air Fryer temperature might change. It’s best to close the door and manually adjust the timer.TIPS:Drain canned tuna. If not properly drained, you will encounter a runny Tuna Salad. Toasting the bottom bread slices first will keep the bottom bread sturdy. Immediately serve once the Tuna Melt is removed from the Air Fryer to avoid soggy bread underneath. I used 4 ounces chunk mild cheddar cheese and then divided into 6 equal slices. Three slices would fit one Tuna Melt sandwich. You may opt to use store-bought pre-sliced cheddar cheese and use 1 slice per sandwich.I used kosher salt sparingly since mild cheddar cheese slices were added.