1. Peel the root vegetables and chop them into smaller pieces, roughly 2x2 cm or 3/4x3/4 inches in size.

2. Slice the onion and set it aside for later use.

3. Place the chopped root vegetables in a large pot, pour in the broth, and bring the mixture to a boil. Reduce the heat and let it simmer covered until the vegetables are tender.

4. Add the sliced onion and sausages to the pot. If you're using a spicy sausage, you might not need additional seasoning, but for a milder sausage, consider adding thyme and bay leaves for extra flavor.

5. In a small bowl, mix the mustard and sour cream together to create a tangy topping to serve alongside the stew.