We clean the tenderloin from fat and films, cut into 1.5 cm medallions. Finely chop the onion, cut the mushrooms into plates. Fry the tenderloin until cooked, about 5 minutes on each side. Put on a plate, cover with foil and keep warm. In the pan put onions and give, stirring, about 4 minutes. Then add the mushrooms and fry for another 5 minutes. Add the flour and fry, stirring, for 1 minute. Then pour in soy sauce and cream, add salt to taste, cook the sauce, stirring until slightly thickened.