In a bowl, combine chicken with soy sauce, dark soy sauce, MSG, garlic powder, salt, crushed black pepper, and cornflour.

Mix well until the chicken is evenly coated. Set aside for 10–15 minutes.

In a separate bowl, whisk together soy sauce, oyster sauce, rice vinegar, dark soy sauce, MSG, crushed black pepper, cornflour, and water.

Stir until smooth and set aside.

Heat oil in a large wok or skillet over medium-high heat.

Add the marinated chicken and cook for 5–6 minutes until lightly golden and nearly cooked through.

Remove chicken from the pan.

Add the chopped garlic and sauté for 30 seconds until fragrant.

Add the bell peppers and stir-fry for 2–3 minutes to keep them crisp yet tender. Add the chicken back.

Give the prepared sauce a quick stir (cornflour tends to settle) and pour it into the pan.

Toss everything together on medium-high heat until the sauce thickens and coats the chicken evenly.

Garnish with freshly crushed black pepper and sesame seeds.

Serve hot with steamed jasmine rice or fried rice.