Before frying, place the halved cheese sticks on a rimmed baking sheet lined with parchment paper. Freeze for 30 minutes.
Meanwhile, assemble the breading and get out the air fryer.
Whisk the mayonnaise and egg together in a medium bowl.
Place the flour, breadcrumbs, onion, and garlic powder in a large bowl and whisk to combine.
Working in batches of 6, roll the frozen cheese sticks in the mayo-egg mixture to coat, then in the flour mixture.
Return the coated cheese sticks to the parchment-lined baking sheet. Repeat with the remaining cheese sticks.
Return the baking sheet to the freezer for 10 minutes.
Heat the air fryer to 370°F.
Fry 6 the mozzarella sticks for 5 minutes -- it is important not to overcrowd the air fryer.
Repeat with the remaining sticks and serve warm with the marinara for dipping.
