Keep around 2 tablespoons of sweet corn kernels aside, put the remaining in a grinder and make a paste.
Heat oil in a pot. Add grated ginger, garlic, and saute for a few seconds.
Add chopped carrot, French beans, the white part of spring onion, and sweet corn kernels. Saute for around 3-4 minutes.
Add the corn paste and saute for about a minute.
Next, add salt, pepper, sugar, and green chili sauce. Mix, and saute for a few seconds.
Add water, mix everything and boil for 4-5 minutes.
In a bowl mix corn starch with around 1/4 cup of water and add to the boiling soup. Stir continuously for around a minute so that no lumps get formed. Cook until the soup thickens.
Finely add vinegar and green part of spring onion. Cook for another minute and then switch off the gas.
Garnish with chopped spring onion and ground black pepper. Serve hot.