Wash the parsley, dab dry and chop finely. Press the sausage mixture into a bowl and mix with the parsley. Season to taste with salt and pepper. Heat vegetable stock. Use 2 teaspoons to cut off small dumplings from the herb sausage mixture and let them simmer in the stock.
Clean, wash and dry mushrooms. Melt the fat in a pan. And fry the mushrooms briefly. Season with salt and pepper, drain and add to the soup. Season soup with salt and pepper and serve.