Combine the well-drained tuna, light mayonnaise, Dijon mustard, hot sauce (if you like it spicy!), finely chopped celery, diced red onion, chopped pickles, jalapeños (if using), garlic powder, salt, and pepper in a medium mixing bowl. Stir everything together until it's perfectly combined and creamy.
Set your air fryer to preheat at 350°F (175°C) for a few minutes while you get your bread ready.
Place your bread slices directly into the air fryer basket. Toast them for about 1-2 minutes until they're slightly golden and firm. This little trick helps keep your melts from getting soggy! Carefully remove the bread.
Evenly spread a generous amount of your delicious, healthy tuna salad mixture over each of the lightly toasted bread slices, covering them completely.
Next, place a thin layer of shredded mozzarella cheese over the tuna. Lay a fresh tomato slice on top of that, and then sprinkle with a little more cheese for ultimate meltiness!
Carefully transfer your loaded tuna melts back into the preheated air fryer basket. Air fry for 4-5 minutes, or until the cheese is wonderfully melted and bubbly, and the bread edges are golden and crispy. If you want a more golden-brown cheese top, increase the heat to 400°F (200°C) for the last minute.
Once done, gently remove the open-faced tuna melts from the air fryer. Let them cool for just a minute or two to prevent burning your mouth on the hot cheese. Dig into your quick, easy, and satisfying summer meal!