Peel the turnips (if not frozen) and potatoes and cut into small cubes. Peel and roughly dice the onions. Peel and slice the carrots.
Heat the butter in the saucepan. Sweat the onions in it over low heat while stirring. Add the potatoes, turnips and carrots. Also sweat well, then deglaze with the stock.
Bring to the boil, add the sausages and let everything simmer for 45 minutes (if there are fewer ingredients, 30 minutes is sufficient). Season the stew with salt, pepper and a little parsley. If you have a sensitive stomach, add some caraway seeds.
Now do not puree the soup very finely with a hand blender. Serve with fresh bread and butter.