Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Cut the chicken breast into 1-inch cubes and place them in a bowl with the broccoli florets, sea salt, black pepper, and half of the sesame oil.
Toss the chicken and broccoli until evenly coated, then spread them in a single layer on the prepared baking sheet.
Roast for 15-18 minutes, or until the chicken is cooked through and the broccoli is tender-crisp.
While the chicken roasts, whisk together the orange juice, coconut aminos, rice vinegar, honey, minced ginger, minced garlic, and arrowroot powder in a small saucepan.
Place the saucepan over medium heat and simmer for 3-5 minutes, whisking constantly until the sauce thickens into a glossy glaze.
Remove the chicken and broccoli from the oven, transfer to a large mixing bowl, and pour the warm orange glaze over the top.
Toss gently to coat every piece, then garnish with sesame seeds and serve immediately.