Preheat oven to 400°F and line a large baking sheet with parchment paper.
Cut the chicken breast into 1-inch bite-sized cubes and toss in a bowl with avocado oil, sea salt, and black pepper.
In a small saucepan over medium heat, whisk together orange juice, tamari, rice vinegar, honey, minced garlic, and grated ginger.
Create a slurry by mixing arrowroot powder with a teaspoon of water, then whisk it into the sauce until thickened and glossy.
Spread the chicken and broccoli florets on the baking sheet in a single layer.
Drizzle half of the orange sauce over the chicken and broccoli, tossing to coat thoroughly.
Bake for 15-18 minutes until the chicken is cooked through and the broccoli is tender-crisp with slightly charred edges.
Serve the baked chicken and broccoli over the warm brown rice, drizzling with the remaining sauce and garnishing with sesame seeds.