Dab the meat dry and cut into strips. Peel onion and cut into fine slices. Clean, wash and halve the mushrooms
Heat the oil in a coated pan. Brown the meat in it. Season with salt and pepper and remove. Sauté the onion and mushrooms in the hot frying fat. Add the meat, dust with flour and sauté briefly. Deglaze with 1/8 l water. Bring to the boil and simmer for about 5 minutes
Cut the cucumbers into small pieces, add them and simmer briefly. Wash and chop the herbs. Stir mustard, sour cream and herbs into the meat. Season to taste. Add the bread rolls