Preheat your air fryer to 400°F to ensure a hot start for the potatoes.
Slice the russet potato into thin, uniform wedges and toss them in a bowl with half of the 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 halfway through, until golden and tender.
While the potatoes cook, whisk together the flour, arrowroot starch, garlic powder, salt, pepper, and light beer in a shallow bowl 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.
Mist the fish lightly with the remaining avocado oil and place it in the air fryer basket, cooking at 375°F for 10-12 minutes until the coating is crunchy and the fish flakes easily.
Serve the fish and chips immediately while hot with a fresh lemon wedge for a bright finish.