Cut the chicken into strips and place them in a bowl. Add soy sauce, salt, and black pepper, then toss to ensure an even coating. Allow the chicken to marinate while you prepare the batter.
In another bowl, sift together the flour, cornstarch, and baking soda. Pour in the beaten egg and cold sparkling water, stirring gently until just combined. Do not overmix.
If desired, lightly dust the marinated chicken with a little extra flour to help the batter stick. Dip each piece into the batter, allowing excess to drip off.
Heat vegetable oil in a deep pan to 350°F. Carefully add the battered chicken in small batches. Fry for 2-3 minutes per side until the batter is crisp and the chicken is cooked through.
Remove and drain on paper towels. Serve with your favorite dipping sauce if desired.
