Preheat the oven to 425°F (220°C). Line a large sheet pan with parchment paper or lightly grease it.
In a small bowl, whisk together the soy sauce, olive oil, honey, minced garlic, and grated ginger until well combined.
Place the chicken thighs in a large bowl and pour half of the garlic soy marinade over them. Toss to coat evenly and let marinate for 10 minutes at room temperature.
In a separate large bowl, combine the red bell pepper, yellow bell pepper, zucchini, red onion, and broccoli florets. Pour the remaining half of the marinade over the vegetables and toss to coat.
Arrange the marinated chicken thighs skin-side up on the prepared sheet pan, spacing them evenly.
Spread the marinated vegetables around the chicken thighs in a single layer.
Season the chicken and vegetables lightly with salt and freshly ground black pepper.
Roast in the preheated oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the vegetables are tender and slightly caramelized.
If desired, switch the oven to broil for the last 2-3 minutes to crisp the chicken skin and vegetables, watching carefully to avoid burning.
Remove the sheet pan from the oven and let rest for 5 minutes.
Garnish with sesame seeds and sliced green onions before serving.