First, press sauté on pressure cooker. In a Ziplock bag, add 2 tablespoons tapioca flour, chicken and pepper. Toss until chicken is fully coated.
Place chicken in pressure cooker and sauté for 2 minutes on each side. Then, press cancel.
Add all remaining ingredients (except tapioca flour, broccoli and green onions) to the pressure cooker. Secure lid and pressure cook on high for 4 minutes.
Let pressure naturally release for 10 minutes, then carefully push valve to Vent and release remaining pressure.
Take 2 tablespoons of the juice inside the pot and add to a small bowl. Then, whisk in remaining tapioca flour until combined.
Next, add this sauce to the pot and press sauté. Sauté for 2 to 3 minutes, or until sauce has thickened.
Finally, serve with cooked broccoli and green onions if desired.