Preheat your air fryer to 400°F (200°C).
Slice the russet potato into thin wedges and toss them in a bowl with 1 teaspoon of avocado oil, half of the sea salt, and half of the black pepper.
Place the potato wedges in the air fryer basket and cook for 15-18 minutes, shaking halfway through, until they are golden and tender.
While the potatoes cook, prepare the batter by whisking together the flour, baking powder, garlic powder, paprika, and the remaining salt and pepper in a shallow bowl.
Slowly pour the cold light beer into the flour mixture, whisking until a smooth, thick batter forms.
Pat the cod fillet completely dry with paper towels, then dip it into the batter to coat all sides thoroughly.
Lightly grease the air fryer basket with the remaining 1 teaspoon of avocado oil, place the battered fish inside, and air fry at 375°F for 10-12 minutes until the coating is crispy and the fish flakes easily with a fork.
Serve the hot fish alongside the potato wedges immediately.