Slice the chicken thigh fillets into strips about half an inch wide and two inches long. Place in a bowl. Add all the ingredients for the marinade. Mix. Cover with cling film and keep in the fridge for about an hour.
About 15 minutes before meal time, cut all the vegetables.
Heat the cooking oil in a wok. When smoking, add the chicken and garlic with the marinade and cook until no longer pink. Remember to keep the chicken strips moving by alternately tossing, swirling and stirring to ensure even cooking and to prevent scorching.
Add the carrot slices and mushrooms next. Stir fry for 30 seconds. Add the asparagus and sliced onion (adding the sliced onion toward the end of cooking time prevents them from turning soggy — remember that this is a stir fry and not a sauteed dish). Stir fry for another 30 seconds.
Make the sauce by stirring together the broth, oyster sauce, soy sauce, sugar and starch. Pour into the wok. Stir until the sauce is thick and clear. Turn off the heat. Transfer the chicken chop suey in a platter and serve at once.