In a large saucepan saute carrot, celery, onion in a small amount of butter until veggies are softened. Add a dash of salt. Add water, potatoes and chicken bouillon. Boil until potatoes are just about tender; 5 - 7 min. Add smoked kielbasa and sauerkraut. Bring to a boil; reduce heat to medium low, and simmer about 5 min. or until potatoes are tender. Remove about 1 c. of cooking liquid from soup along with about 1/2 cup of the potato chunks. Mash the potato chunks and stir together with sour cream in a small bowl; add back the liquid with the potato mash to the soup, along with the sour cream. Heat through. Taste for seasoning. Add salt and pepper if needed. Serve warm!