Heat 1 tablespoon oil and sauté onions for 2 minutes. Add mushrooms and sauté for a further 2 minutes. Season with salt and a pinch of pepper. Cool.
Puree until smooth, adding a little milk if necessary.
Add 1 tablespoon corn flour to ¼ cup of the cold milk.
Mix remaining milk with the mushroom and onion puree and bring to a boil. Add the cold milk and corn flour and take off heat when thick. Omit corn flour if you do not want a thick soup. Serve hot with a dollop of cream (optional)
Recipe Notes
Any available variety of mushrooms can be used for this soup.