Slice the potato into 1/2-inch thick wedges and toss with avocado oil, sea salt, and garlic powder.
Place potato wedges in an air fryer at 400°F for 15-20 minutes until crispy and tender.
Pat the cod fillets dry with paper towels to ensure the batter sticks properly.
In a medium bowl, whisk together arrowroot starch, gluten-free flour, baking powder, and black pepper.
Slowly pour the chilled beer into the flour mixture, whisking until a smooth, thin batter forms.
Dip each cod fillet into the batter, allowing excess to drip off, then place in the air fryer basket.
Air fry the fish at 375°F for 10-12 minutes, flipping halfway through, until the coating is shatteringly crisp.
Serve the hot fish and chips immediately with a fresh lemon wedge for brightness.