In a bowl, add all the ingredients for the chicken marinade. Mix everything together and coat the chicken well. Set aside for 10 mins
Cook the chicken by frying or baking. To fry, add the chicken in hot vegetable oil and fry until golden brown. Remove from oil and set aside. Make sure to have a large enough frying pan so that the chicken pieces don't stick together. To bake, preheat the oven to 220°C (430 F). Grease a large baking tray and place your chicken pieces on to the tray, making sure the pieces don't touch. Spray with an oil spray and bake for 20 mins, flipping the chicken pieces after 10 mins. Set the baked/fried chicken aside
In a bowl, mix vinegar, soy sauce, oyster sauce, sriracha sauce and cornstarch. Set aside.
In a wok or a large deep pan, add oil, chopped garlic and ginger and sliced white end of the green onion. Saute at medium flame until the ginger garlic turns light golden brown.
Add a splash of water, tomato paste, brown sugar and salt. Stir for 2 mins to allow tomato paste to cook for a bit. Add more water if the paste splatters a lot.
Drop in all your vegetables and saute for another minute.
Add 2 cups of water and allow the the water to come to a boil.
After the water boil, add the cornstarch sauce mix and the fried/baked chicken.
Cook for another 2 to 3 minutes or until gravy thickens.
Turn off flame and sprinkle sesame seeds and green onions for garnish
Serve with fried rice.