Cut your cod into strips about 4 inches long and 1 inch wide, pat dry with paper towels and season with salt and pepper
Whisk a cup of all purpose flour with 1/2 teaspoon of baking powder, 1/2 teaspoon of garlic powder, 1/2 teaspoon of onion powder, 1/2 teaspoon of paprika, 1/2 teaspoon of salt and a pinch of cayenne pepper in a large bowl
Slowly add the sparkling mineral water or beer, whisking as you go, until a thick, but whiskable batter comes together (this should take about 1 cup). Transfer the batter into the refrigerator until your oil is ready for frying
Place a large heavy bottom skillet over medium to medium high heat and add 2 inches of a neutral oil
Once the oil is between 350°-375°, dip a piece of cod into the chilled batter until all sides are coated
Carefully dip the batter coated cod into the hot oil repeat with 2-3 more pieces (avoid crowding the oil with too many pieces of fish)
Once the batter is golden brown and crispy, carefully remove the fried fish from the oil using a large slotted spoon or spider strainer and transfer them onto a cooling rack
Season the freshly fried fish lightly with salt
Repeat the process until all of the fish is fried