Scrub the potato and cut into half-inch thick wedges, then pat them dry with a clean towel.
Toss the wedges with half of the avocado oil and a pinch of the sea salt, then air fry at 400 degrees Fahrenheit for 15 minutes until crispy.
Pat the cod fillets completely dry with paper towels to ensure the batter adheres properly to the surface.
In a shallow bowl, whisk together the flour, baking powder, garlic powder, paprika, black pepper, and the remaining sea salt.
Stir in the beer and the remaining avocado oil until a thick, smooth batter forms without over-mixing.
Dip each cod fillet into the batter to coat it fully, allowing any excess to drip off before placing it in the air fryer basket.
Air fry the fish at 375 degrees Fahrenheit for 10 to 12 minutes, flipping halfway through, until the coating is golden and shattered-crisp.