Pat the cod fillets dry with paper towels. This ensures the batter will stick properly to the fish.

Mix the flour, cornstarch, baking powder, and salt in a large bowl.

Gradually whisk the beer into the flour mixture. Mix until the batter is smooth and thick.

Dust each fish fillet with a bit of flour. This helps the batter cling better.

Dip the fillets into the batter, ensuring they're well coated.

Heat the oil in a deep fryer or large pan to 350°F. Gently place the fillets in the hot oil.

Fry until golden and crispy, roughly 4–5 minutes on each side.

Drain on paper towels, season with salt, and serve with lemon wedges.