Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the chicken breast into 1-inch uniform cubes and place them in a bowl, seasoning with sea salt and black pepper.
In a small whisking bowl, combine the orange juice, tamari, honey, arrowroot powder, grated fresh ginger, minced garlic, and sesame oil until smooth.
Place the chicken cubes and broccoli florets onto the prepared baking sheet in a single layer.
Pour half of the orange sauce over the chicken and broccoli, tossing well to ensure every piece is evenly coated.
Bake for 15 to 18 minutes, or until the chicken is cooked through and the broccoli is tender-crisp with slightly charred edges.
While the chicken bakes, pour the remaining sauce into a small saucepan over medium-low heat and simmer for 2-3 minutes until it thickens into a glossy glaze.
Serve the baked orange chicken and broccoli over the warm brown rice, drizzling with the extra thickened glaze.
Garnish with toasted sesame seeds and sliced green onions before serving.