Preheat oven to 400°F and line a large baking sheet with parchment paper.
Cut the chicken breast into 1-inch cubes and season with sea salt and black pepper.
Place chicken and broccoli florets on the baking sheet, drizzle with toasted sesame oil, and toss to coat evenly.
Roast in the oven for 15-18 minutes until the chicken is cooked through and the broccoli is tender-crisp.
While roasting, whisk the fresh orange juice, tamari, honey, rice vinegar, minced fresh ginger, minced garlic, and arrowroot powder in a small saucepan.
Simmer the sauce over medium heat for 3-5 minutes until it thickens into a glossy glaze.
Remove the chicken and broccoli from the oven and transfer to a large bowl.
Pour the orange glaze over the chicken and broccoli, tossing gently to coat every piece.
Garnish with sesame seeds and green onion before serving.