Preheat the oven to 425째F (220째C).
Place the potato strips in a large bowl and toss with vegetable oil and a pinch of salt.
Spread the potatoes in a single layer on a baking sheet.
Bake for 25-30 minutes, turning halfway through, until golden and crispy.
In a bowl, whisk together the flour, baking powder, salt, and pepper.
Gradually add the cold sparkling water or beer, whisking until the batter is smooth. The batter should be thick enough to coat the fish fillets.
In a large, deep skillet or frying pan, heat about 2 inches of vegetable oil to 350째F (175째C).
Pat the fish fillets dry with paper towels.
Dip each fillet into the batter, allowing any excess to drip off.
Carefully place the battered fish into the hot oil.
Fry for 4-5 minutes per side, or until golden brown and crispy. The fish should flake easily with a fork.
Remove the fish from the oil and drain on paper towels.
Enjoy your meal!