Marinate the chicken with egg, salt, 1tbsp cornflour and keep aside for at least 1hr.
Take a wok heat 3tbsp oil. Stir fry the chicken for on medium heat till cooked and golden. Keep aside.
For the sauce heat 1-2 tbsp of oil in the same wok. Add ginger, garlic and whole black pepper and cook for 5 min. Now add crushed black pepper, soya sauce, vinegar, chicken and spring onions,cook it for 5 min. Add chicken stock cook till chicken turns tender.
Add 2tbsp of cornflour in 1/2 cup of water.pour it and stir till it turn a thick sauce. Add Salt and sugar.mix it well give it a standing time for 5min. Serve hot