Prepare the Ingredients: Slice the chicken and vegetables into bite-sized pieces for even cooking.
Make the Sauce: In a small bowl, whisk together chicken broth, soy sauce, oyster sauce, sesame oil, cornstarch, and water until smooth. Set aside.
Cook the Chicken: Heat 1 tbsp of oil in a wok or skillet over medium-high heat. Add the chicken and stir fry until fully cooked. Remove and set aside.
Stir Fry Vegetables: Add the remaining oil to the wok. Toss in the mushrooms, broccoli, carrots, snow peas, and water chestnuts. Stir fry for 3-4 minutes until tender-crisp.
Combine Chicken and Sauce: Return the chicken to the wok. Pour the prepared sauce over the ingredients, stirring well to coat everything evenly.
Simmer the Sauce: Allow the sauce to thicken by cooking for 1-2 minutes, stirring constantly.
Serve Hot: Transfer to a serving dish, garnish with green onions or sesame seeds if desired, and enjoy with steamed rice or noodles.