Cut the chicken into small bite-sized pieces then add the egg, salt, black pepper, and corn flour then mix until the chicken is evenly coated.
Set aside and as it marinates finely dice the garlic cloves, slice the green chillies, and cut the onion and bell peppers into chunks.
Once you have prepared your veggies, heat up some oil in a pan until medium-hot then add the chicken pieces into the oil and deep fry for 4-5 minutes until crispy and golden (See Note 1)
In a separate wok heat up two tbsp of oil, then add the garlic cloves and green chillies and sauté for 1 minute until fragrant.
Add the onion and bell peppers then cook for 2-3 minutes until softened.
Add the soy sauce, vinegar, tomato ketchup, chilli sauce, and brown sugar then cook for a few minutes. (See Note 2)
In a small bowl combine the water and cornflour then mix until it is smooth and there are no lumps before adding to the wok then bring the mixture to a boil. (See Note 3)
Add the cooked chicken and cook until the desired consistency is reached.
Garnish with spring onions then serve with rice and enjoy!