In a medium bowl, combine 1 cup of all-purpose flour, ½ cup of whole milk, and ½ cup of cold water. Add ¼ teaspoon of baking powder and 1 teaspoon of salt to the mixture. Whisk until smooth.

In a deep skillet or fryer, pour enough oil to submerge the fish fillets and heat it to 365°F (185°C). Test with a small piece of batter.

Pat the fish fillets dry with paper towels to remove moisture, ensuring crispiness.

Dip each dried fish fillet into the batter and allow excess to drip off before placing it in the hot oil.

Fry the fillets for about 2 minutes on each side or until golden brown and crispy.

Remove the fried fish with a slotted spoon and drain on a cooling rack over paper towels.