In a small bowl, whisk together the tamari, rice vinegar, honey, arrowroot powder, toasted sesame oil, red pepper flakes, and water to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the cubed chicken breast to the skillet and cook until golden brown and cooked through, approximately 5-6 minutes.
Add the minced garlic and grated ginger to the pan, stirring for 30 seconds until the aromatics are fragrant.
Toss in the broccoli florets along with a tiny splash of water, then cover with a lid for 2 minutes to steam them until vibrant green and tender-crisp.
Remove the lid and pour the prepared sauce mixture over the chicken and broccoli.
Stir constantly for 1-2 minutes until the sauce bubbles and thickens into a glossy glaze that coats every piece.
Transfer to a plate and garnish with sesame seeds before serving.