Heat large skillet on medium heat. Add oil, then garlic. Cook garlic until translucent and fragrant, then add chicken.
Cook chicken for about 2 minutes, then add sesame seed oil, soy sauce, rice vinegar and oyster sauce. Cook mixture for about another 5 minutes or until chicken is cooked. Add zucchini and cook until tender, about 1-2 minutes.
Before serving, sprinkle with sesame seeds, ground black pepper and chopped cilantro.