Bring the potato cubes and carrot pieces together with the celery, bay leaf and the finely chopped parsley root with the vegetable stock to a boil. Add so much vegetable stock that the vegetables are covered about 2 fingers wide. After about 10 minutes add the leek rings and continue cooking until the potatoes and carrots are cooked through.
Fish out the celery (if you like, you can also dice the celery and eat it), add the chopped sausages and let them steep warm. Season to taste with salt and pepper.