Cut the chicken breast into bite-sized pieces and season with sea salt and black pepper.
In a small bowl, whisk together the orange juice, orange zest, coconut aminos, grated ginger, and arrowroot starch until the starch is fully dissolved.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the skillet in a single layer and sear until golden brown and cooked through, approximately 5-6 minutes. Remove the chicken from the pan and set aside.
Add the broccoli florets and sliced red bell pepper to the same skillet, adding a tablespoon of water if needed to help steam the vegetables until they are tender-crisp.
Stir in the minced garlic and cook for 30 seconds until fragrant, being careful not to burn it.
Return the cooked chicken to the skillet and pour the prepared orange sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens into a glossy glaze that coats the chicken and vegetables.
Serve the stir-fry immediately over the warm cooked brown rice and garnish with sliced green onions.