- Stock:
 - 2 tablespoons vegetable oil
 - 3 pounds turkey bones
 - 1 onion, quartered
 - 1 stalk celery, coarsely chopped
 - 1 carrot, coarsely chopped
 - 16 cups water
 - 2 sprigs fresh thyme
 - Soup:
 - 2 1/2 cups water
 - 1 cup barley
 - 2 tablespoons olive oil
 - 1 onion, diced
 - 2 carrots, sliced
 - 2 stalks celery, sliced
 - 2 cloves garlic, minced
 - 2 cups chopped cooked turkey
 - 1/4 cup chopped fresh parsley
 - 2 sprigs fresh thyme, leaves stripped
 - 1/4 teaspoon salt
 - 1/4 teaspoon ground black pepper
 - 1/8 teaspoon cayenne pepper
 - 1/2 lemon, juiced
 
- Heat vegetable oil in a large stockpot over medium-high heat. Add turkey bones to hot oil; cook, turning occasionally, until browned, about 10 minutes. Transfer bones to a bowl.
 - Cook and stir quartered onion, coarsely chopped celery, and coarsely chopped carrot in the hot oil in the same stockpot until fragrant, about 2 minutes. Return turkey bones to stockpot and add 16 cups water and thyme sprigs. Bring to a boil, skim off foam, reduce heat to medium-low, and simmer until liquid reduces to 10 cups, about 2 hours. Strain stock into a large bowl and let stand for 15 minutes. Spoon fat off top of stock.
 - Bring 2 1/2 cup water and barley to a boil in a saucepan. Cover saucepan, reduce heat to low, and simmer until the barley is tender, 30 to 40 minutes.
 - Heat olive oil in a large stockpot over medium-high heat; cook and stir diced onion, sliced carrots, sliced celery, and garlic until slightly softened, about 5 minutes. Add turkey stock to onion mixture and bring to a boil.
 - Mix turkey meat, barley, parsley, thyme leaves, salt, black pepper, and cayenne pepper into soup; reduce heat to medium-low and simmer for 20 minutes. Stir lemon juice into soup.