Cut 1 pound of boneless chicken thighs into bite-sized pieces. Combine cornstarch, light soy sauce, sesame oil, sugar or honey, and optional rice wine vinegar in a mixing bowl to create a marinade. Coat the chicken in this mixture and let it marinate for about 30 minutes.

Heat 1 tablespoon of cooking oil in a large skillet or wok over medium-high heat until it shimmers.

Add smashed garlic cloves to the hot oil and sauté for about 30 seconds. Add marinated chicken to the pan, spreading it out evenly. Stir-fry for about 2-3 minutes until no longer translucent, then remove chicken and set aside.

In the same pan, add sliced zucchini and stir-fry for approximately 5 minutes until bright green and slightly crisp.

Return cooked chicken to the pan with zucchini. Add 1 tablespoon of oyster sauce and ground black pepper to taste, mixing well. Cook for an additional 2-3 minutes.

Remove from heat and serve immediately with rice or noodles.