Preheat oven to 400°F and line a large baking sheet with parchment paper.
In a small bowl, whisk together the orange juice, tamari, honey, minced ginger, minced garlic, sesame oil, and arrowroot powder until the starch is fully dissolved.
Place the cubed chicken breast and broccoli florets on the prepared baking sheet and season with sea salt and black pepper.
Pour half of the orange sauce mixture over the chicken and broccoli, tossing well to ensure every piece is evenly coated.
Bake for 15-18 minutes, or until the chicken is cooked through and the broccoli reaches a tender-crisp texture.
While the chicken bakes, pour the remaining sauce into a small saucepan and simmer over medium heat for 2-3 minutes until it thickens into a glossy glaze.
Serve the baked chicken and broccoli over a bed of warm brown rice, drizzled with the extra glaze and garnished with sesame seeds and sliced green onions.