Preheat your air fryer to 400°F to ensure a hot cooking environment for the potatoes.
Slice the russet potato into half-inch thick wedges, keeping the skin on for extra fiber and texture.
Toss the potato wedges in a bowl with the avocado oil and a pinch of the sea salt until evenly coated.
Place the wedges in the air fryer basket in a single layer and cook for 18-20 minutes, shaking halfway through.
While the potatoes cook, whisk together the flour, baking powder, garlic powder, and black pepper in a shallow dish.
Slowly pour the light beer into the flour mixture, whisking gently until a thick, smooth batter forms.
Pat the cod fillets very dry with paper towels and season both sides with the remaining sea salt.
Dip each cod fillet into the beer batter, allowing any excess to drip off before placing them in the air fryer.
Once the potatoes are done, remove them and keep warm; place the fish in the air fryer at 375°F for 10-12 minutes until the crust is golden and firm.
Serve the crispy fish immediately alongside the hot potato wedges for a clean version of this pub classic.