01 - Cut chicken breasts into thin strips approximately 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 uniformly combined.
03 - Lightly beat the egg in a separate bowl, then incorporate the ice-cold sparkling water.
04 - Pour wet mixture into dry ingredients. Stir briefly with chopsticks or fork just until combined, leaving batter slightly lumpy. Do not overmix.
05 - Heat vegetable oil in deep pan or fryer to 350°F.
06 - Dip seasoned chicken strips into batter, allowing excess to drip off.
07 - Carefully add battered chicken to hot oil. Fry in batches for 3-4 minutes until golden and crisp, turning once. Avoid overcrowding the pan.
08 - Transfer cooked chicken to wire rack or paper towels to drain excess oil.
09 - Combine soy sauce, mirin, rice vinegar, sugar, and ginger in small saucepan. Heat gently until sugar dissolves completely. Cool to room temperature before serving.
10 - Arrange chicken tempura on serving plate and serve immediately with dipping sauce on the side.