Sift together the flour, cornstarch, baking soda, baking powder, and salt to ensure even distribution and a smooth batter. Gradually incorporate the water, stirring thoroughly until the mixture is fully blended and free of lumps. Submerge fish or chicken filets completely in the batter, coating each piece uniformly. Fry in hot oil until the coating turns a crisp and golden brown.
Notes
Quantities can be increased proportionally based on the volume of fish or chicken being prepared.