Polish sauerkraut soup can be made with bits of smoked meat and bacon or strictly vegetarian. It's your preference.
I didn't use salt because the sauerkraut is fairly salty. Taste before you salt.
Also, I originally added a sprinking of caraway seeds but was told that caraway was more Czech than Polish. However, according to a reader, caraway helps cut the gas. Add it if you like. I personally love it.