In a small bowl, whisk together the fresh orange juice, tamari, minced ginger, minced garlic, arrowroot starch, and toasted sesame oil until the starch is fully dissolved.
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 shimmering.
Add the chicken to the skillet and cook until golden brown and cooked through, approximately 6 to 8 minutes, then remove the chicken from the pan and set aside.
In the same skillet, add the broccoli florets, sliced red bell pepper, and snap peas, stir-frying for 4 to 5 minutes until the vegetables are tender-crisp.
Return the cooked chicken to the skillet and pour the prepared orange sauce over the chicken and vegetable mixture.
Toss everything together for 1 to 2 minutes until the sauce thickens into a glossy, translucent glaze.
Serve the stir-fry over a combined bed of cooked brown rice and cauliflower rice, then garnish with sesame seeds and sliced green onions.