Clean, wash and slice the mushrooms. Peel onions and cut into half rings. Wash, dry and cut the meat into strips. Heat oil. Brown the meat in portions, season. Take out
Fry the mushrooms and onions in the frying fat for about 5 minutes, season. Dust with flour and sweat it on. Deglaze with 1 1/2 l water and boil up. Stir in broth. Add meat and braise covered for 35-40 minutes
Cut the cucumbers into sticks. Add the peppercorns to the soup about 15 minutes before the end of the cooking time and warm up. Stir in mustard and sour cream, bring to the boil again. Season to taste with salt and pepper. Garnish with parsley