Slice the chicken breast into thin, bite-sized strips and set aside.
In a small bowl, whisk together the tamari, rice vinegar, toasted sesame oil, and red pepper flakes to create the stir-fry sauce.
Finely mince the garlic and grate the fresh ginger.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the chicken strips to the skillet and sear until golden brown and cooked through, approximately 5-6 minutes.
Remove the chicken from the pan and set it aside on a plate.
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.
Uncover and add the minced garlic and grated ginger, sautéing for 1 minute until highly fragrant.
Return the chicken to the pan and pour the prepared sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens slightly and coats the ingredients evenly.
Garnish with sesame seeds before serving hot.