- In a saucepan, heat oil on medium flame, add ginger and garlic and saute for a couple of minutes, once fried add in the onions. Cook the onions until they turn transparent. Next add the finely chopped carrots, coriander leaves and mix. In a small mixing bowl, combine the corn flour along with 1/4 cup of water until there are no lumps. At this stage add water, cornflour mixture and bring the soup to a rolling boil. While the soup is coming to a boil, add in the salt and pepper. Finally, once the Lemon Coriander Soup has come to a boil, turn off the flame and add in the lemon juice. Mix well and serve hot.