Pour oil to a hot pan. When the oil turns hot, regulate the flame to high and add fine chopped garlic, ginger, chilli and coriander stems.
Saute for 30 seconds and add spring onion whites and onions. Fry until onions turn golden.
Add shredded cabbage, chopped beans, bell peppers, mushrooms and carrots. Fry stirring constantly for 2 minutes until you smell the veggies aromatic.
Pour 4 cups of water or broth and bring it to a rolling boil.
Meanwhile stir together 1½ tablespoon cornstarch with 3 to 4 tbsps of water to make a smooth slurry. Reduce the heat slightly and keep stirring with a ladle and slowly incorporate the corn slurry into the boiling manchow soup.
Cook until the soup turns slightly thick. Add coriander leaves and spring onions.
Pour soya sauce and add ½ teaspoon salt and crushed pepper. Stir and taste test. Adjust the quantity of soya sauce, salt and pepper to your taste.
Turn off when the manchow soup thickens, do not overcook we want the veggies crunchy. Keep this covered until served. Stir in the vinegar when you are ready to serve.
Boil the noodles following the instructions on your pack of noodles. Make sure you cook them al dente and not mushy.
Once cooked, drain to a colander and rinse them under running water to get rid of the starch.
You can also skip all of the following steps and serve the soup with boiled noodles. To fry them proceed further. Shake off the colander to remove all the excess water and spread the noodles on a tray. Let them air dry for 30 minutes until completely dry.
Sprinkle 2 to 2½ tablespoons cornstarch all over the noodles and mix gently to coat the noodles with the flour.
Heat 1 cup oil in a frying pan until hot enough. When the oil is hot, drop some noodles to to the oil and fry until they turn crisp on the base.
Turn them to the other side and fry again until crisp and light golden. Remove them from oil when they are crisp. Continue to fry all of the noodles in 4 to 5 batches ensuring the oil is hot enough before every batch.
Ladle the soup to serving bowls. Top with crispy noodles and green onions. If you prefer you may add some chilli vinegar or any hot sauce.