Turn off the heat and let cool slightly.
Take half of the mushroom mixture and blend with a little water to a fine paste.
Return the mushroom paste to the pot and add some water after rinsing the blender jar.
Mix well, adding about ½ cup of water more.
Whisk in the milk and add salt to taste. Bring to a boil.
At this stage, if you feel the soup is thick, add some water. Dilute with more water till you get the consistency you want.
Taste for salt and simmer for about 5 to 7 minutes. Sprinkle with black pepper powder; give it a good stir.
Serve hot creamy mushroom soup, garnished with finely chopped green onions, along with toasted bread or croutons!
Notes
If you feel like avoiding flour for thickening the soup, you can use whole wheat flour or omit it altogether.If you feel the soup is thick, add more water or milk as needed.