Preheat oven to 400°F and line a large baking sheet with parchment paper.
In a small mixing bowl, whisk together the fresh orange juice, tamari, honey, grated ginger, minced garlic, and arrowroot powder until smooth.
Place the cubed chicken breast on the baking sheet and season with sea salt and black pepper.
Pour half of the orange glaze over the chicken and toss to ensure every piece is thoroughly coated.
Bake the chicken for 10 minutes, then remove the tray from the oven and add the broccoli florets.
Drizzle the remaining glaze over the broccoli and chicken, tossing gently to combine.
Return the tray to the oven and bake for an additional 8 to 10 minutes until the chicken is cooked through and the broccoli is tender-crisp.
Garnish the dish with sesame seeds and sliced green onions before serving warm.