Thinly slice the chicken breast.
In a bowl, place sliced chicken breast and pour half of the sauce. Mix well and rest while you prepare the vegetables.
Meanwhile, slice bok choy's. Core and slice bell peppers into thin strips. Cut the green onions.
Heat a large skillet (I use 12-inch skillet) over medium high heat.
Add oil. When it’s simmering add the chicken and spread it out evenly all over the skillet. Cook the meat, undisturbed, for 1-2 minutes, or until they’re nicely browned on the bottom. Then gently stir to cook other side, another 2 minutes. Transfer the chicken onto a clean plate.
Add the white part of green onions, bok choy, and bell pepper and stir fry for 2-3 minutes.
Pour in the remaining half of the stir-fry sauce and cook until thickened, about a minute.
Stir in the chicken and cook until chicken is heated through, about another minute or so.
Serve immediately with some rice and green part of green onions.