01 - Cut chicken breasts into thin strips measuring 1/2 x 2 inches. Pat thoroughly dry with paper towels and season evenly with salt and pepper.
02 - Whisk together flour, cornstarch, and baking powder in a mixing bowl until well combined.
03 - Lightly beat the egg in a separate bowl, then incorporate the ice-cold sparkling water.
04 - Pour the wet mixture into the dry ingredients. Stir briefly with chopsticks or a fork, leaving the batter slightly lumpy—avoid overmixing for optimal texture.
05 - Heat vegetable oil in a deep pan or fryer to 350°F.
06 - Dip seasoned chicken strips into the batter, allowing excess to drip off before carefully adding to the hot oil.
07 - Fry in batches for 3 to 4 minutes until golden and crisp, turning once halfway through. Avoid overcrowding the pan to maintain oil temperature.
08 - Transfer cooked chicken to a wire rack or paper towels to drain excess oil.
09 - Combine soy sauce, mirin, rice vinegar, sugar, and ginger in a small saucepan. Heat gently until sugar completely dissolves, then cool to room temperature.
10 - Arrange chicken tempura on a serving plate and serve immediately with dipping sauce on the side.