Combine in a large pan, yellow onions, celery, carrots, bell pepper in oil and saute for 5 minutes.
Add chicken and mushrooms.
Cover and cook for about 6 minutes.
Add salt, pepper, soy sauce and chicken stock.
Let it simmer for 10 minutes.
Mix 3/4 cup of water with cornstarch till smooth.
Stir smooth into pot, stirring fast and bring it to a boil.
Switch off the flame.
Let it set for a few minutes.
:- Serve over cooked Basmati Rice, Fried Noodles, Green Tea.