1 1/2 cups soda water, plus more if necessary
1 cup all-purpose flour
1/2 cup cornstarch
1 tablespoon baking powder
1 teaspoon cayenne pepper
Combine the cornstarch and 1/2 cup of soda water in a small bowl and whisk to blend.
Whisk together the flour, baking powder, and cayenne pepper.
Add the remaining cup of soda water and stir to blend.
Whisk in the cornstarch mixture.
Cover the bowl with plastic wrap and set aside for 10 minutes.
Fill a deep frying pan or pot with 2 inches of canola oil and heat to 350 F over medium high heat.