Preheat your air fryer to 400°F (200°C) to ensure a hot cooking environment for maximum crunch.
Slice the Russet potato into 1/2-inch thick wedges, then toss them in a bowl with 0.5 tbsp of avocado oil and a pinch of sea salt.
Place the potato wedges in the air fryer basket in a single layer and cook for 15-18 minutes, shaking the basket halfway through, until they are golden and crispy.
While the chips cook, pat the cod fillets extremely dry with paper towels and cut them into large, even strips.
In a small mixing bowl, whisk together the flour, light beer, garlic powder, smoked paprika, and the remaining sea salt and black pepper until a smooth, thick batter forms.
Remove the chips from the air fryer and keep them warm; lightly grease the air fryer basket with a small amount of avocado oil.
Dip each fish strip into the beer batter, allowing any excess to drip off, and place them carefully into the air fryer basket.
Lightly spray or brush the tops of the battered fish with the remaining avocado oil and air fry at 400°F for 8-10 minutes, flipping gently halfway through, until the coating is set and the fish flakes easily with a fork.
Serve the hot fish alongside the crispy potato wedges with an optional fresh lemon wedge.