Boil water in a saucepan with salt. Once the water starts bubbling, add noodles and cook till they are al dente or cooked through.
Drain water from the boiled noodles, transfer them to a colander, and wash them under cold water to prevent more cooking. Let them sit in the colander to drain out all the water for 15 - 20 minutes. You can do this process at night and store the noodles in the refrigerator.
Next heat oil in a deep-fry pan over medium-high flame. Deep fry boiled noodles in small batches in the hot oil till crisp from both sides. Drain on a paper towel to get rid of excess oil. Similarly, fry all the noodles. Set them aside.
Once noodles are fried prepare the sauce for the chop suey. Combine soy sauce, red chili sauce, and tomato sauce. Stir to mix nicely. Set aside.
Prepare Chop Gravy:
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.
To serve the Chinese chop suey, in a bowl add the sauce topped with fried noodles or vice versa. Sprinkle chopped spring onion on top along with sesame seeds. Serve Chinese Chop Sue immediately.
Chop Suey is best consumed hot, crispy, and fresh. After assembling, do not leave it for too long else fried noodles will become soggy.