Slice the russet potato into thin wedges, toss with half of the avocado oil and a pinch of sea salt, then air-fry at 400°F for 15-18 minutes until crispy.
Pat the cod fillets completely dry with paper towels to ensure the batter adheres properly to the surface.
In a small bowl, whisk together the flour, garlic powder, paprika, and the remaining sea salt and black pepper.
Slowly pour the cold beer into the flour mixture, whisking gently until a smooth, thick batter forms without over-mixing.
Dip each cod fillet into the batter, coating thoroughly, and allow any excess to drip off before cooking.
Lightly grease the air fryer basket with the remaining avocado oil, place the fish inside, and cook at 375°F for 10-12 minutes, flipping halfway, until the crust is shattered-crisp.
Serve the hot fish and chips immediately with a fresh lemon wedge for a zesty, bright finish.