8 ounces uncooked black barley
1 small bunch fresh thyme
2 bay leaves
1/4 teaspoon black peppercorns
of 1 orange
1/4 cup diced parsnip (1 small parsnip)
1/4 cup diced carrot (1 small carrot)
1/4 cup celery root (1 small root)
1 tablespoon unsalted butter
freshly ground black pepper
flat-leaf parsley leaves, for garnish
Put barley in a bowl. Pour enough cold water over it to cover by about 1 inch. Set aside to soak for about 24 hours.
Lay an 8-inch square double thickness of cheesecloth on a work surface. Pile the thyme, bay leaves, peppercorns, and orange zest in the center of the cheesecloth. Tie the corners together to make a bouquet garni.
Drain the barley. Transfer it to a large pot. Add 4 cups of water and the bouquet garni. Stir once or twice. Bring to a boil over medium-high heat. Reduce the heat to medium-low. Simmer very gently for 25 to 30 minutes, or until the barley is tender.
If necessary, drain the excess liquid from the pot. Add the parsnip, carrot, celery root, and butter. Stir to mix. Continue cooking over medium heat for 6 to 8 minutes, or until the vegetables are tender and the butter melts. Season to taste with salt and pepper, garnish with the parsley, and serve.