Wash the meat, dab dry and cut into strips. Heat oil in a pot and fry the meat in portions at high heat. Season with salt and pepper. Remove from the pot and set aside.
Peel onions and cut them into strips. Clean the mushrooms, wash if necessary and cut into slices. Add onions and mushrooms to the frying fat and fry for about 5 minutes, turning occasionally.
Season with salt and pepper. Dust with flour and sweat it. Deglaze with broth while stirring and bring to the boil. Add the shredded meat and cook at low heat for 10-15 minutes. Meanwhile cut cucumbers into sticks and add them to the soup together with the peppercorns shortly before the end of the cooking time.
Stir in the cream. Season to taste with mustard, salt and pepper. Serve garnished with parsley as desired.