Stir Fry chicken with vegetables

I found this recipe from cook book called Practical Cookery Chinese. I made a lot of change that it is not that recipe anymore. I had to change name to because recipe used duck.Also,  I added more vegetables and made it spicy adding chili paste. Chicken is very crispy with this recipe because marinated with cornstarch and egg white. I love it.
Ingredients

1 egg white
2 tbsp cornstarch
1 lb skinless boneless chicken breast
1/4 cup vegetable oil for fry the chicken
1 red bell pepper
half head of broccoli
half head f cauliflower
1 cup snow peas
2 small zucchini

2 tbsp light soy sauce
2 tsp Chinese rice wine vinegar
1 tsp brown sugar
1/2 cup chicken stock or water
1 tbsp chili paste ( optional )

Preparation Method
In a mixing bowl beat together the egg and cornstarch.
Using a sharp knife cut the chicken into small pieces and stir into the egg white mixture. Leave to stand for 30 minutes.
Heat the oil in a preheated pan.Remove the chicken from the egg white mixture, add to the pan and fry in the oil for 5 minutes, until crisp. Remove the chicken from the oil set aside.
Add all the vegetables stir fry 5 minutes.And then add the cooked chicken.
Stir in the soy sauce, Chinese rice vinegar, sugar and chicken stock, optional chili paste and bring to a boil.
Serve immediately.