Wash and dry the bok choy. Cut off and discard the root end of the bok choy; separate the leaves.
Cut off and discard the root end of the scallions; thinly slice on an angle, separating the white bottoms and green tops.
Peel and mince or shred the ginger. Pat the chicken dry with paper towels and chop into bite-sized pieces.
Season the chicken with salt and pepper. Brown the chicken in the oil, with the diced onion.
Add the bok choy, white bottom of the scallions, poison sauce, rice vinegar, sesame oil and ginger to the pan; season with salt and pepper. Cook, stirring occasionally, 2 to 3 minutes, or until the bok choy has wilted.
To the pan, add the hoisin sauce, ½ cup of water. Season with salt and pepper. Cook, stirring occasionally, 10 to 12 minutes, or until the chicken is thoroughly coated and cooked through.