In a mixing bowl, combine the teriyaki sauce, minced garlic, minced ginger, and a pinch of salt and pepper. Mix well.
Place the chicken thighs in a large resealable bag or a baking dish and pour half of the teriyaki marinade over them. Seal the bag or cover the dish and let marinate in the refrigerator for at least 30 minutes (or up to 2 hours for maximum flavor).
While the chicken is marinating, prepare the vegetables. In a large bowl, toss the broccoli, red bell pepper, carrot, and snap peas with olive oil, salt, and pepper until evenly coated.
Line a large sheet pan with parchment paper or foil for easy cleanup. Arrange the marinated chicken on one side of the pan and the seasoned vegetables on the other side.
Drizzle the remaining teriyaki marinade over the chicken.
Roast in the preheated oven for 25-30 minutes or until the chicken is cooked through (internal temperature should reach 165°F/75°C) and the vegetables are tender.
Remove the sheet pan from the oven, drizzle with extra teriyaki sauce if desired, and sprinkle with sesame seeds and chopped green onions for garnish.
Let it rest for a couple of minutes before serving.
Notes
For extra flavor, let the chicken marinate longer if time allows.