In a pan, combine the bok choy, onion, bean sprouts and chicken stock. Cover and cook on high for 5-10 minutes or until the veggies have wilted and cooked down by almost half.
Remove lid and allow any liquid in the pan to cook down. A little is okay, but you don't want a lake.
Toss in the chicken and stir well.
Stir in the peanut butter. It will clump in the beginning, but if you keep stirring, it will disperse and cover everything nicely.
Remove from heat and allow to cool slightly.
Notes
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.