In a medium bowl, combine the shredded cabbage, mayonnaise, dill pickle relish, lemon juice, and Dijon mustard. Stir until the cabbage is evenly coated, then set the slaw aside while you prepare the fish.

Set up three shallow dishes for breading. Place the flour in the first dish, the beaten eggs in the second, and the panko breadcrumbs mixed with garlic powder, paprika, salt, and black pepper in the third.

Pat the cod fillets dry with a paper towel. Dredge each fillet in the flour, shaking off excess, then dip it in the egg, and finally press it into the seasoned panko to coat both sides.

Lightly spray both sides of the coated fillets with cooking oil. Place them in a single layer in the air fryer basket, working in batches if needed to avoid crowding.

Air fry at 400°F for 10 to 12 minutes, flipping halfway through, until the crust is golden and the fish flakes easily with a fork.

Serve the hot cod fillets with a generous scoop of the tartar slaw on the side.