Cut the chicken into bite-sized pieces.
Season lightly with salt and black pepper.
In a bowl, whisk together the flour, cornstarch, and baking powder.
In a separate bowl, lightly beat the egg. Add the ice-cold water and mix gently.
Slowly add the flour mixture to the wet ingredients, stirring lightly. The batter should be slightly lumpy—don’t overmix.
In a deep frying pan or wok, heat about 2 inches of oil to 350°F (175°C).
Test the oil by dropping in a small amount of batter—if it sizzles and floats immediately, it’s ready.
Dip each piece of chicken into the tempura batter, letting the excess drip off.
Carefully place the chicken in the hot oil, frying in batches to avoid overcrowding.
Fry for about 3-4 minutes per side, or until golden brown and fully cooked.
Remove and place on a wire rack or paper towels to drain excess oil.
Serve the chicken hot with your favorite dipping sauces. Enjoy!