Boil water in a pot, add noodles, and cook it for 8-10 minutes on high flame. Strain the water, and add salt and cornstarch to them.
Take a wok, and heat oil in it. Now add the noodles, and fry them on high flame till they turn golden brown. Set the fried noodles aside for later.
Boil water in the same pot as the noodles, and add all the vegetable trimmings. Boil and simmer for 15 minutes (or longer for more flavor).
In a skillet, strain the excess oil from wok, and saute ginger, garlic, and green chilies on high flame for a minute.
Strain the vegetable stock, and add it to the wok. Continue cooking on high flame and bring it to a boil.
Add cabbage, carrots, french beans, and mushrooms. Saute and let them cook on high flame.
Add soy sauce, black pepper powder, salt, and sugar. Give them a nice mix.
Make a cornstarch slurry in a small bowl, and pour it slowly into the broth while simultaneously stirring and mixing with the spatula to thicken the soup.
Finally, garnish it with coriander leaves, and while serving add fried noodles on top.
Your veg manchow soup is ready to be served.