1Heat butter in a saucepan over medium-high heat; add onion, and cook, stirring, until soft, about 5 minutes. Add barley, and cook, stirring, until lightly toasted, about 5 minutes.
2Add stock, potato, carrot, celery root, leek, marjoram, sausages, and bacon, and cook, stirring occasionally, until sausages are tender, about 35 minutes.
3Remove sausages and bacon from saucepan, thinly slice sausages, and discard bacon. Season soup with nutmeg, salt, and pepper. To serve, ladle soup into 8 serving bowls, and garnish with parsley and sliced sausage.