Chop the capsicum and onion into chunky pieces (like you would for a kebab on a skewer) and then chop the spring onion and separate the green part from the white and the middle. Also chop the chicken into bite size pieces.
Marinate the chicken with salt, pepper, sesame oil, vinegar, soya sauce and chilli sauce. Let it marinate for 20 minutes
Heat the olive oil in a wok and fry the ginger, garlic and green chillies. Once the garlic starts to turn brown, add in the chicken.
You want to cook this at the highest heat possible and give it all a good mix.
Once the chicken is halfway cooked you can add in the spring onion middle and whites, the onion and the green bell pepper. If you want the veggies to have more crunch you can add them in later on, more towards the end of the cooking.
Now give everything a good mix and keep moving it around in the wok and cook till the juices released by the meat have turned into a nice thick sauce and has coated all the veggies as well.
Now that the chicken has cooked, the veggies too and the sauce is the the consistency you like, finish with the spring onion greens and give it all once last good mix.