Step 1: In a large bowl, whisk together the flour, cornstarch, baking powder, salt, garlic powder, paprika, black pepper, and cayenne pepper if using. Pour in the cold beer and the beaten egg, whisking until the batter is smooth and slightly thick. It should coat the back of a spoon but still flow easily.

Step 2: For an extra crispy crust, prepare the optional flour coating by mixing the additional flour with garlic powder, paprika, salt, and pepper in a shallow dish. This step adds another layer of crunch and helps the batter stick better to the fish.

Step 3: In a deep skillet, Dutch oven, or fryer, heat about 2–3 inches of vegetable oil to 350°F (175°C). Use a thermometer to monitor the oil temperature to ensure proper frying.

Step 4: Pat your fish fillets dry thoroughly with paper towels. If using the optional flour coating, dredge each fillet in the seasoned flour first, shaking off any excess. Dip the floured fish into the batter, allowing the excess to drip off before frying.

Step 5: Carefully place the battered fish into the hot oil, frying in batches to prevent overcrowding. Fry each piece for 4 to 6 minutes per side, or until the crust is golden brown and the internal temperature reaches 145°F (63°C). Remove with a slotted spoon and place on a paper towel-lined plate to drain.

Step 6: Serve the fish hot and crispy with sides like fries, coleslaw, or hushpuppies. Add tartar sauce, lemon wedges, or cocktail sauce for the full experience.