Heat oil in a work. Add chopped garlic, ginger, celery, and fry for 1 minute to release the flavor into the oil. No need to brown them.
Add chopped onion and again stir fry over high heat for 1 minute.
Next, add the diced vegetables, cabbage, and stir-fry over high heat for the next 1 -2 minutes to cook the vegetables yet keep them crunchy.
Add salt, pepper, white vinegar, and stir fry for 10 - 20 seconds.
Add the sauce mix and water. Stir to combine, and simmer the gravy for 2 - 3 minutes.
Combine corn starch with water, make a smooth paste, and add to the bubbling gravy. Stir continuously to avoid any lump formation. Allow chop suey gravy to simmer for 2 - 3 minutes or till it thickens a bit. Turn off the heat.