01 -
Heat vegetable oil in a deep fryer or heavy saucepan to 350°F (177°C).
02 -
In a medium mixing bowl, combine flour, cornstarch, baking powder, kosher salt, and cayenne pepper. Whisk in cold water steadily until the batter is smooth and slightly foamy.
03 -
Pat fish fillets dry with paper towels to remove excess moisture. Dip each fillet into the batter, ensuring all sides are evenly coated.
04 -
Carefully lower fillets into hot oil. Fry for 3 to 4 minutes until the exterior is crisp and golden brown, separating pieces if needed to prevent sticking.
05 -
Transfer the cooked fish to a wire rack set over a tray to drain off excess oil before serving.