Cut boneless chicken thighs into bite-sized pieces. In a mixing bowl, combine cornstarch, light soy sauce, sugar or honey, and minced garlic to create your marinade. Toss the chicken to coat it evenly in the marinade. Let it rest for 30 minutes to absorb the flavors.

Heat a wok or large skillet over medium-high heat and add a tablespoon of neutral cooking oil. Once heated, add the marinated chicken and cook for about 2-3 minutes, stirring frequently until the chicken turns golden and is fully cooked. Transfer the chicken to a plate and set aside.

In the same pan, add a splash more oil, and toss in sliced zucchini. Stir-fry on high heat for approximately 5 minutes, stirring regularly to ensure even cooking. The zucchini should become slightly tender yet crisp.

Return the cooked chicken to the pan along with any accumulated juices. Pour in the oyster sauce and stir-fry the mixture for another 2-3 minutes, ensuring all elements are heated through and well combined.

Remove the pan from the heat. Garnish with ground black pepper or sesame seeds if desired. Serve your Chicken Zucchini Stir Fry over steamed rice or toss it with noodles.