Coat the chicken with salt, pepper and oyster sauce.
Refrigerate while preparing the remaining items.
Combine the flour, cornstarch, and baking powder in a bowl and mix well.
Add the egg and stir until batter is smooth.
Heat the oil to 375 C.
Working in small batches, coat the chicken in the batter and carefully place in the oil. If you place too much chicken in at once, it can cool the oil down too much.
Cook for 5-7 minutes and then turn the chicken over; cook for another 5-7 minutes, or until golden brown.
Remove the chicken from the oil and drain on paper towels.