In a marinating bowl, combine hoisin sauce, soy sauce, Worcestershire sauce, and red pepper flakes(optional). Stir in the pork cutlets. cover the bowl then stick it in the fridge to marinate for 2-3 hours.
In a wok or a saute pan, heat up oil. Add the garlic to cook for a few seconds. Add the marinated pork cutlets. Set aside the marinade in the bowl. Stir in the pork cutlets and garlic, cover the pan, then let that cook for 15-20 minutes.
Put the onion rings into the marinating bowl to coat the onions with the marinade. Add the onions into the wok next. Stir in water and continue to cook until the onions soften slightly. Less than 5 minutes.
Stir in the mushroom to cook for 2-3 minutes
Lastly, stir in the cornstarch mixture to thicken the sauce.
