In a small bowl, whisk together the tamari, honey, rice vinegar, arrowroot powder, minced ginger, minced garlic, and red pepper flakes to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the diced chicken breast to the skillet and cook until golden brown and cooked through, about 5-7 minutes.
Remove the chicken from the skillet and set aside.
Add the broccoli florets and sliced red bell pepper to the same skillet, adding a splash of water if needed to steam-cook until tender-crisp.
Return the chicken to the skillet and pour the sauce over the mixture.
Stir constantly for 1-2 minutes until the sauce thickens into a glossy glaze.
Remove from heat and stir in the toasted sesame oil.
Serve the stir-fry over the cooked brown rice and garnish with sliced green onions and sesame seeds.