To make corn paste, combine sweet corn kernels and water in a food processor or blender. Make a coarse paste and set aside.
Heat oil in a saucepan or a wok.
Add chopped ginger, garlic and stir-fry for a 10 - 20 seconds or till the aroma of herbs are released.
Next, add the chopped spring onion and stir-fry for a minute.
Add all the vegetables including corn kernels and fry for 5 minutes.
Now, add the corn paste and stir to combine nicely.
Add water, soy sauce, chili vinegar, salt, pepper, mix well and cook on a medium flame for another 4 to 5 minutes, while stirring occasionally.
While the soup is simmering, combine cornflour with 1/4 cup of water and make a smooth paste.
Slowly, with a steady flow add the cornflour slurry to the simmering soup. Make sure soup is not boiling while adding the cornflour. Stir continuously to avoid lump formation.
Allow the soup to simmer for next few minutes until it thickens to the desired consistency.
Garnish sweet corn soup with spring onion greens.
Serve Chinese Sweet Corn Soup warm.