Cook chicken over medium heat until done. Steam green beans and mushrooms until beans are tender and crisp.
Mix soy sauce, water, peanut butter, cayenne, and garlic in a small microwaveable container. Microwave sauce for 45-60 seconds. Stir sauce until smooth. Toss cubed chicken in sauce until well coated.
Plate the chicken with a healthy serving of the green bean & mushroom medley. Add just a dash of soy sauce to the finished vegetables.