Toss chicken with the soy sauce and cooking wine and set aside for a few minutes. Lightly whip the egg whites until just frothy then whisk through the cornflour.
Heat the oil in a deep frying pan.
Dip the chicken into the batter and shake off excess.
Fry the chicken pieces for around six minutes, turning after three minutes, until lightly brown all over. Drain excess oil.
For the sauce
Bring the sugar, vinegar, calamansi juice, salt and stock to a boil in a small saucepan or clean wok.
Add the carrot and spring onion and toss until the vegetables are softened.
Stir in the cornstarch mixture and cook for about one minute until thickened.
Slice the chicken and arrange it on top of the shredded lettuce.
Pour the sauce over that and serve.