Preheat your Blackstone griddle over medium-high heat.
In a bowl, combine the chicken pieces, soy sauce, sesame oil, garlic, and ginger. Let it marinate for at least 15 minutes.
Once the griddle is hot, add the vegetable oil.
Add the marinated chicken to the griddle and cook for about 5-7 minutes, stirring occasionally, until the chicken is browned and cooked through.
Push the chicken to one side of the griddle and add the sliced onion, broccoli, zucchini, mushrooms, and carrots to the other side. Cook the vegetables for about 5-7 minutes until tender.
Mix the chicken and vegetables together on the griddle and cook for an additional 2-3 minutes. Season with salt and pepper to taste.
Remove from heat and sprinkle with chopped green onions and sesame seeds if desired.
Serve hot, either on its own or with steamed rice or noodles.