Prepare your ingredients by chopping the chicken into bite-sized pieces and slicing the vegetables thinly.

In a mixing bowl, marinate the chicken with soy sauce, oyster sauce, and sesame oil for about five minutes.

Heat oil in a large skillet over medium-high heat. Add marinated chicken and stir-fry until golden brown (about five minutes).

Add garlic to the skillet, then toss in carrots, bell peppers, and cabbage. Stir-fry until vegetables are vibrant and tender-crisp (about three to four minutes).

Mix additional soy sauce with sugar in a small bowl; pour over stir-fried ingredients and combine well.

Serve hot on plates or in bowls; garnish with sesame seeds if desired.