Prepare Ingredients: Slice the chicken breast into thin strips and season with a pinch of salt and pepper. Cut all vegetables as directed to ensure they cook evenly.

Heat the Oil: In a large pan or wok, heat the vegetable oil over medium-high heat until shimmering.

Cook the Chicken: Add the sliced chicken and stir-fry for 4-5 minutes, or until the chicken is fully cooked and lightly browned.

Sauté Aromatics: In the same pan, add the sliced onion and minced garlic. Stir-fry for 1-2 minutes until fragrant and the onion begins to soften.

Add Vegetables: Add the bell pepper, carrots, broccoli florets, and snap peas to the pan. Sauté for 3 to 4 minutes, or until the vegetables reach a tender-crisp texture.

Combine Ingredients: Return the cooked chicken to the pan with the vegetables. Pour in the soy sauce and optional oyster sauce, stirring to coat everything evenly.

Thicken the Sauce: Stir the cornstarch slurry, then pour it into the pan. Mix well and cook for another 1-2 minutes, allowing the sauce to thicken and coat the ingredients.

Presentation: Adjust the seasoning with extra salt and pepper according to your preference before serving. Serve hot over a bed of cooked rice or noodles, and enjoy!