Heat vegetable oil in a large skillet or wok over medium-high heat. Add sliced chicken and cook for 4-5 minutes, stirring occasionally, until the chicken is cooked through and lightly browned. Remove from the skillet and set aside.

In the same skillet, add sliced onion, mushrooms, snow peas, and carrots. Sauté for 3-4 minutes until the vegetables are tender but still crisp.

Add minced garlic and cook for another minute until fragrant.

In a small bowl, whisk together chicken broth, soy sauce, oyster sauce, and cornstarch mixture.

Return the cooked chicken to the skillet and pour the sauce over the chicken and vegetables. Stir everything together and simmer for 2-3 minutes until the sauce thickens slightly.

Season with salt and pepper to taste. Serve immediately over rice if desired.