Slice the russet potato into thin wedges and soak them in a bowl of cold water for 10 minutes to release excess starch.
Preheat your air fryer to 400°F.
Drain the potato wedges and pat them completely dry with a clean kitchen towel, then toss with half of the avocado oil and a pinch of sea salt.
Arrange the potatoes in a single layer in the air fryer basket and cook for 15 minutes, shaking the basket halfway through.
While the potatoes cook, whisk together the flour, light beer, paprika, remaining sea salt, and black pepper in a shallow bowl until a smooth batter forms.
Pat the cod fillets dry with a paper towel, dip them into the batter to coat all sides, and lightly mist or brush with the remaining avocado oil.
Place the battered fish in the air fryer basket alongside the potatoes and cook for an additional 10 minutes, flipping the fish once, until the crust is shattered-crisp and the fish is opaque.
Serve the hot fish and chips immediately with a fresh lemon wedge for a bright, zesty finish.