Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Dice the chicken breast into one-inch cubes and season them evenly with sea salt and black pepper.
In a small mixing bowl, whisk together the fresh orange juice, tamari, honey, grated ginger, minced garlic, and arrowroot powder until the starch is fully dissolved.
Place the chicken cubes and broccoli florets in a bowl, drizzle with sesame oil, and toss to coat before spreading them in a single layer on the baking sheet.
Bake for 12 minutes, then remove from the oven and pour the orange sauce mixture over the chicken and broccoli, tossing with tongs to ensure everything is glazed.
Return the tray to the oven for an additional 5 to 7 minutes until the sauce has thickened into a sticky coating and the chicken is cooked through.
Scoop the cooked brown rice into a bowl and top with the hot orange chicken and broccoli.
Garnish with sesame seeds and thinly sliced green onions before serving.