Mix all the sauce ingredients in a medium size bowl until completely smooth.
Add the olive oil to the bottom of a fry pan and heat to medium high. Add the cut-up chicken and cook until the chicken is golden brown and almost cooked through, about 10 minutes.
Add the sauce to the chicken and toss until all the chicken is coated. Add the broccoli floret pieces and sliced mushrooms to the chicken mixture; stir until coated. Let the chicken and veggie mixture simmer for about 10 minutes.
