Heat a 6-quart Dutch oven on medium-high until hot. Add thighs; cook until browned, turning once, about 8 minutes. Transfer to a bowl. Repeat with breasts.
Add broth, wine, celery, carrot, and garlic to Dutch oven. Bring to a boil; scrape any browned bits from pot; return chicken to pot, reduce heat, and simmer, skimming as necessary, for 1 hour. Transfer chicken to a plate; let cool. Transfer vegetables to another plate; reserve.
Add leeks, prunes, and barley to broth. Bring to a boil, reduce heat, and simmer until thick, about 40 minutes more. Once chicken has cooled, shred meat. Finely dice carrot and celery. Stir chicken, carrot, celery, and parsley into soup, heat through, and serve.
This is a delicious, rich, flavorful soup. I thought the prunes sounded strange, but they add wonderful flavor and blend nicely. A perfect winter soup.
I have been making this soup each January for several years now for my son's Robert Burns party (the Scottish Poet). I make so much that I use an entire case of leeks. My son tells me that everyone loves it and looks forward to it each year. Thanks for the great recipe!
This soup is fabulous and delicious. The prunes add a warm, rich flavor that is not obviously identifiable as dried plums. They cook into the soup and take on the flavor of the broth - without them this soup would be so much less! This soup is a savory and comforting dish to make any time of year.