Preheat your air fryer to 400°F.
Slice the russet potato into thin wedges and pat them thoroughly dry with a paper towel.
In a bowl, toss the potato wedges with 1 teaspoon of avocado oil and half of the sea salt, black pepper, and garlic powder.
Place the potatoes in the air fryer basket in a single layer and cook for 15-18 minutes, shaking halfway through, until golden and crisp.
While the potatoes cook, pat the cod fillets dry and season with the remaining salt, pepper, garlic powder, and paprika.
In a shallow bowl, whisk together the arrowroot powder, almond flour, and light beer until a smooth, thin batter forms.
Dip each cod fillet into the batter, ensuring it is fully coated, and let any excess drip off.
Once the potatoes are done, remove them and keep warm. Lower the air fryer temperature to 375°F.
Lightly grease the air fryer basket with the remaining teaspoon of avocado oil and place the battered fish inside.
Air fry the fish for 10-12 minutes, flipping carefully halfway through, until the coating is crispy and the fish flakes easily with a fork.