Adapted from Gardenguru's Tempura Batter
1 cup flour
1/4 cup cornstarch
1/4 teaspoon salt
1 teaspoon baking powder
1 cup Club soda or Beer As cold as possible), more as needed
Oil for deep-frying (I used canola Oil)
Mix flour, cornstarch, salt, and baking powder.
Add soda water gradually, stirring with a fork, first to create a paste and then until mixture is like a thick pancake batter.
Heat oil for frying to 360° F -375°F.
Dry Fish well. Dip into batter letting excess drip off before carefully slipping into hot oil.
Do not crowd pan.
Drain on paper towels.