Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Place the broccoli florets on the baking sheet, drizzle with half of the avocado oil and a pinch of sea salt, then roast for 15-20 minutes until tender and charred at the edges.
While the broccoli roasts, cut the chicken breast into one-inch cubes and season evenly with sea salt and black pepper.
In a small bowl, whisk together the orange juice, coconut aminos, honey, arrowroot powder, minced garlic, and grated ginger until smooth.
Heat the remaining avocado oil in a large non-stick skillet over medium-high heat.
Add the chicken to the skillet in a single layer and sear for 5-6 minutes, turning occasionally, until golden brown and cooked through.
Reduce the heat to medium and pour the orange sauce mixture over the chicken.
Stir constantly for 1-2 minutes until the sauce bubbles and thickens into a glossy glaze that coats the chicken.
Remove from heat and serve the orange chicken over the roasted broccoli, garnishing with sesame seeds and sliced green onions.