In a small bowl, whisk together the tamari, honey, rice vinegar, minced ginger, and minced garlic to create the teriyaki sauce.
Season the cubed chicken breast evenly with the sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the chicken to the skillet and sauté until golden brown and cooked through, approximately 5 to 6 minutes, then remove the chicken and set it aside.
In the same skillet, add the broccoli, red bell pepper, carrots, and sugar snap peas, stir-frying for about 4 minutes until the vegetables are vibrant and tender-crisp.
Return the cooked chicken to the skillet and pour the teriyaki sauce over the mixture.
Toss everything together constantly for 1 to 2 minutes until the sauce has thickened and created a glossy glaze over the chicken and vegetables.
Remove from the heat and drizzle with the toasted sesame oil.
Serve the stir-fry immediately over the warm cooked brown rice and garnish with sliced green onions and sesame seeds.