Slice the chicken breast fillet in small pieces. Put them into a small bowl. Add the cornflour, ginger and crushed garlic. Pour the soy sauce and mix well. Set aside to marinate.
Put a wok or a large pot on the heat. Add one tablespoon of vegetable oil, then chopped onion. Stir briefly then add mushroom and chopped carrots, broccoli and bell peppers. Cook on low heat until just tender.
While the vegetables are cooking, put a frying pan on medium heat. Pour in the remaining spoon of vegetable oil. Add the chicken and reserve the marinade for later. Fry the chicken on both sides until well cooked. Add the marinade and stir.
When the vegetable are ready, add the chicken mixture into it and stir. The food is ready and can be served with rice. Enjoy!