Step 1: Marinate the Chicken

• In a bowl, mix the chicken strips with soy sauce and cornstarch.
• Let it marinate for at least 15 minutes while you prepare the other ingredients.

Step 2: Prepare the Sauce

• In a small bowl, combine soy sauce, oyster sauce, dark soy sauce, chicken broth, sugar, black pepper, and white pepper.
• Stir well and set aside.

Step 3: Cook the Chicken

• Heat 1 tbsp of vegetable oil in a large pan or wok over medium-high heat.
• Add the marinated chicken and stir-fry for 3-4 minutes until golden and cooked through.
• Remove the chicken from the pan and set aside.

Step 4: Stir-Fry the Vegetables

• In the same pan, add another tablespoon of oil.
• Sauté the onion, garlic, and ginger for 1-2 minutes until fragrant.
• Add the mushrooms and bell pepper, and stir-fry for another 3 minutes until softened.

Step 5: Combine Everything

• Return the cooked chicken to the pan.
• Pour the prepared black pepper sauce over the ingredients and mix well.
• Add the cornstarch slurry and stir until the sauce thickens.
• Toss in the green onions and stir for another minute.