In a large bowl, whisk together marinade ingredients. Add chicken to bowl and let marinade about 4 hours.
Make the sauce: in a small sauce pan on medium heat, whisk together coconut aminos, rice vinegar, garlic, sesame oil, ginger, honey, salt and if using, red pepper flakes. Bring to a low boil. Whisk in tapioca flour/water mixture. Lower heat and continue to simmer until thickened, about 10 minutes. Set aside.
Heat a large nonstick skillet over high heat. Add 1 tbsp coconut oil. Add broccoli and pinch of salt and stir fry until broccoli is bright green, but crisp, about 3-5 minutes. Remove and set aside.
Lower heat to medium high and add chicken. Stir fry until chicken is cooked through, about 5-6 minutes. If you like some extra spice, you can add some extra red pepper flakes.
Add broccoli back into skillet. Add about 3/4 of the sauce to skillet, reserving some to use as extra topping.
Serve with rice and garnish with green onions if desired.