Heat oil in a large skillet over medium-high heat.  Season chicken thighs on both sides with salt and pepper and place skin side down in the skillet.  Cook until skin is golden brown, about 5 minutes. Flip the thighs over and continue to cook until golden brown on the other side, about 2-3 minutes.  Transfer thighs to the slow cooker.

Pour off all but 1 tablespoon of fat from the skillet.  Add onion, carrots, celery and garlic and cook over medium heat until vegetables have softened slightly, about 2-3 minutes.  Add thyme and wine and continue cooking, scraping up any browned bits on the bottom of the skillet, until wine has almost completely evaporated, about 1-2 minutes.  Add 3 cups of broth and bring to a boil. Transfer vegetables and broth to the slow cooker.

Add remaining 4 cups broth, pearl barley, bay leaf and soy sauce to the slow cooker.  Cook on high for 3 hours.

Remove chicken thighs from the slow cooker and, using tongs and a fork, shred chicken into bite-sized pieces discarding the skin and the bones.  Skim any excess fat from the surface of the soup. Return shredded chicken to the slow cooker. Add lemon juice and parsley and season to taste with salt and pepper.  Serve.