Prepare the fish:
Pat the fish fillets dry with paper towels to remove any excess moisture. Set aside.

Make the batter:
In a medium bowl, whisk together the flour, salt, garlic powder, onion powder, paprika, black pepper, and baking powder. Add the beaten egg and cold water (or sparkling water) to the dry ingredients, stirring until a smooth batter forms. If the batter seems too thick, add a little more water, one tablespoon at a time, until it reaches a thick but pourable consistency.

Heat the oil:
In a large skillet or deep fryer, heat the vegetable oil over medium-high heat. You want the oil to reach about 375°F (190°C) for optimal frying. To test if the oil is hot enough, drop a small amount of batter into the oil; if it bubbles and rises to the surface quickly, the oil is ready.

Dip and fry the fish:
Dip each fish fillet into the batter, ensuring it’s completely coated. Carefully place the battered fillet into the hot oil. Fry the fillets in batches, if necessary, to avoid overcrowding the pan. Cook for about 4-5 minutes per side or until golden brown and crispy. Remove the cooked fish from the oil and place them on a paper towel-lined plate to drain excess oil.

Serve:
Serve the batter-dipped fish hot with lemon wedges on the side and garnish with fresh parsley, if desired. This dish pairs wonderfully with fries or a side of coleslaw.