This is a family favorite. I made this for my sons when they had International Day at school. All three boys chose Hungary, Poland or Germany for their country, this covered all three! The last time I made this for that occasion was 18 years ago, my youngest is now 23! I make this for all holiday celebrations even for cookouts, keeps well in a crock pot on low or warm setting.
Peel and cut onions. Melt butter/margarine in large dutch oven. Saute the onions until translucent. While the onions are cooking, drain the sauerkraut.
When the onions are done, add the sauerkraut. Saute together until the sauerkraut softens a bit, about 10 minutes, stir occasionally. Add sugar, I start with 1/8 of a cup and add until the "bite" or tartness is gone from the sauerkraut. You don't want it sweet, but the tartness should be less. Cook about 10 minutes.
Add the keilbasa. Cook for 10 minutes, stirring occasionally. Add the potatoes, cooking another 20 minutes on low. Add the potatoes last as they will get too soft if added earlier.
You will know when this is "done" as there will be a great aroma as well as the kraut will be softened and the keilbasa will cook a bit. Serve with rye bread or rolls and mustard on the side. Enjoy!!