In a large bowl, combine chicken pieces, vegetable oil, garlic powder, onion powder, ground ginger, salt, and black pepper. Toss to coat the chicken evenly and let marinate for at least 15 minutes.
Heat a large skillet or wok over medium-high heat. Add the marinated chicken and cook for about 5-7 minutes, stirring occasionally, until the chicken is cooked through and golden brown.
Add the soy sauce and sesame oil to the skillet, stirring to combine. Cook for an additional 2 minutes.
Add the broccoli, bell peppers, and zucchini to the skillet. Stir-fry the vegetables with the chicken for about 5 minutes, or until they are tender-crisp.
Remove from heat and stir in the sliced green onions. If desired, sprinkle with sesame seeds before serving.