Add the onion to the skillet and cook until translucent. Add the mushrooms and cook, turning occasionally, for 7–8 minutes until browned.
Add the frozen edamame. Cook, breaking up the frozen pieces, for 5–6 minutes until the edamame is bright green.
Add the sliced bok choy. Return the chicken to the skillet and pour the sauce on top. Bring to a boil and toss to coat. Cook for 3–5 minutes until the bok choy is wilted.