Prepare the potatoes first. Cut the potatoes into ½-inch thick fries, trying to keep them uniform in size. Soak them in cold water for 15 minutes, then drain thoroughly and pat completely dry with paper towels (moisture is the enemy of crispness).
Season the chips by tossing them in a bowl with 1 tablespoon olive oil, ½ teaspoon salt, ¼ teaspoon pepper, and ½ teaspoon paprika until evenly coated.
Preheat your air fryer to 380°F (195°C) for 3 minutes. This ensures even cooking from the start.
Cook the chips first by arranging them in a single layer in your air fryer basket (work in batches if needed). Cook for 12-15 minutes, shaking the basket halfway through, until golden and crispy. Transfer to a plate and keep warm.
Prepare the fish batter while the chips cook by whisking together flour, baking powder, garlic powder, paprika, salt, and pepper in a medium bowl. Gradually add the cold sparkling water, whisking until smooth. The batter should be thick enough to coat the fish but still drip off slowly.
Pat the fish fillets completely dry with paper towels, then season lightly with salt and pepper on both sides.
Dip each fillet into the batter, letting excess drip off, then place in the air fryer basket that has been lightly sprayed with cooking spray. Avoid overcrowding – cook in batches if necessary.
Spray or brush the coated fish lightly with oil to help achieve that golden color.
Cook the fish at 380°F (195°C) for 10-12 minutes until the coating is crispy and golden and the fish flakes easily with a fork. No need to flip!
Serve immediately with the chips, lemon wedges, malt vinegar if desired, and tartar sauce. Garnish with chopped parsley for a pop of color.