Melt 2 TBS of butter in a large stock pot. Add 1/2 chopped sweet onion and saute until just softening. Add stock. (I kept adding more stock and broth as I went, but altogether I used about 3 cups of homemade chicken stock and 4-14oz. cans of Swanson Chicken broth. So about 10 cups of chicken broth total.) Add four big carrots, in bite sized chunks, two parsnips, also in chunks, two ribs of celery, sliced, and about 3 pounds of redskin potatoes, cut in chunks with the skin on. I also added about six cups of water at this point. Add sauerkraut. I am guessing that I had 8-10 cups of sauerkraut. (This was leftover kraut that had been cooked with pork and caraway seeds, so it was really good. If I was starting with fresh kraut I would probably add some supplemental pork to the soup.) I had five brats that had some nice carmelization that I cut up and added, but kielbasa or smoked sausage would be awesome. Add about 1 t. black pepper and 1 t. white pepper.
Cover and simmer for a couple of hours, until the potatoes are getting soft.
In another pan, melt 3 TBS butter. Add about 1/4 c. chopped mushrooms and 1 t. salt. (I will probably use more mushrooms next time, but I wasn't sure that I wanted them.) Use your flour of choice to make a roux. I used 3 TBS rice flour because I had a bag that had a little left in it that I wanted to finish. Add about 1/2 c. white wine or beer. (Again, more would be good, I had about 1/2 cup left from a box of chardonnay.) Add 1 qt. 1/2 and 1/2, and then, because it doesn't look like enough, add a cup or two of whole milk. Stir until slightly thickened. Add (don't hate me foodie friends!) about 8 oz. of Velveeta. (Because that's how much I had.) Add all of this to the pot and simmer for another 15 minutes, at least. Throw in about 1 TBS of dried parsley.
Makes a lot of soup. :)
Enjoy with crusty bread.