Clean the potatoes and vegetables, cut into small cubes and cook in the vegetable stock until soft. Set aside 4 tablespoons of the cooked potato cubes. Puree the soup in a blender or hand blender.
Return to the pot and bring to the boil. Add the crème fraîche and cream or milk. Cut the sausages into slices and let them get hot in the soup. Add the potato pieces again. Season to taste with salt, pepper and the herbs.