Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Dice the chicken breast into 1-inch cubes and cut the broccoli into small, bite-sized florets.
Spread the chicken and broccoli onto the baking sheet, drizzle with avocado oil, and season evenly with sea salt and black pepper.
Bake for 15-18 minutes until the chicken is cooked through and the broccoli is tender with slightly browned edges.
While the chicken roasts, combine orange juice, tamari, honey, grated ginger, minced garlic, and arrowroot powder in a small saucepan over medium heat.
Whisk the sauce constantly for 3-5 minutes until it simmers and thickens into a glossy, translucent glaze.
Transfer the roasted chicken and broccoli to a large mixing bowl, pour the warm orange glaze over the top, and toss gently to coat every piece.
Serve the orange chicken and broccoli over the cooked brown rice, garnishing with sliced green onions and sesame seeds.