01 - Cut the chicken breasts into thin strips about 1/2 x 2 inches. Pat dry thoroughly with paper towels and season evenly with salt and pepper.
02 - In a mixing bowl, whisk together the all-purpose flour, cornstarch, and baking powder until well combined.
03 - In a separate bowl, lightly beat the egg, then mix it with the ice-cold sparkling water until incorporated.
04 - Pour the wet mixture into the dry ingredients. Stir very briefly with chopsticks or a fork, leaving the batter slightly lumpy—do not overmix as this prevents proper crisping.
05 - Heat the vegetable oil in a deep pan or fryer to 350°F. Maintain temperature throughout frying for optimal results.
06 - Dip the seasoned chicken strips into the batter, allowing excess to drip off, then carefully add to the hot oil.
07 - Fry in batches for 3 to 4 minutes until golden and crisp, turning once halfway through. Do not overcrowd the pan to maintain oil temperature.
08 - Transfer cooked chicken to a wire rack or paper towels to drain excess oil while remaining crispy.
09 - Combine soy sauce, mirin, rice vinegar, sugar, and ginger in a small saucepan. Heat gently until sugar dissolves completely, then cool to room temperature.
10 - Arrange the chicken tempura on a serving plate and serve hot with the dipping sauce on the side.