Dice the chicken breast into bite-sized pieces and season with sea salt and black pepper.
In a small bowl, whisk together the tamari, rice vinegar, maple syrup, arrowroot powder, and red pepper flakes to create the sauce.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat.
Add the chicken to the skillet and cook until golden brown and cooked through, about 5-7 minutes.
Remove the chicken from the pan and set aside.
In the same skillet, add the broccoli florets and sliced red bell pepper with a splash of water, covering for 2 minutes to steam-soften.
Add the minced garlic and grated fresh ginger to the vegetables and sauté for 1 minute until fragrant.
Return the chicken to the skillet and pour the sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens and coats the chicken and vegetables.
Serve the stir-fry over the warm cooked brown rice and garnish with sliced green onions.