Prepare the vegetables and mushrooms. In a frying pan with vegetable oil, fry the onion until transparent, add the carrots and continue frying for 3 minutes. Add the mushrooms, salt, pepper, and simmer until all the liquid has evaporated from the mushrooms. Set aside a few fried mushrooms for serving.
Boil the potatoes. Place the potatoes in a saucepan, add salt, pour in water and cook until done.
Make a puree. Place the fried mushrooms, onions and carrots into a saucepan with the potatoes. Cook together for 10 minutes. Pour the vegetable broth through a sieve and set aside. Puree the soup using a blender, gradually adding cream. Let the soup sit for 5-10 minutes.