1. Bring water, chicken, onion, whole garlic cloves, bay leaves, thyme and parsley sprigs, peppercorns, carrots, and celery to a boil in a pot, skimming foam from surface as necessary. Reduce heat, and gently simmer until broth turns deep gold, about 1 1/2 hours. Let cool, then skim fat from surface.

2. Meanwhile, cook barley according to package instructions.

3. Strain stock, reserving chicken breasts and discarding all other solids. Remove meat from bone, and shred into 2-inch pieces. Reheat stock and chicken in a saucepan, and stir in salt.

4. Just before serving, finely chop remaining parsley with the lemon zest until combined. Heat oil in a skillet over medium-high heat. Add sliced garlic, and cook, stirring, until fragrant but not browned, about 30 seconds.

5. Divide barley, stock, and chicken among 6 bowls. Garnish with sliced garlic and parsley-lemon mixture.