Mushroom Barley Soup

Name: Mushroom Barley Soup
Ingredients: 1/3 cup quick-cooking barley; 7 cups water; 1/4 oz dried porcini (1/4 cup); 1 large leek (white and pale green parts only), halved lengthwise and thinly sliced crosswise; 1 tablespoon olive oil; 1 large onion, chopped; 2 celery ribs, cut into 1/3-inch dice; 2 carrots, chopped; 1/2 lb fresh shiitakes, stems discarded and caps thinly sliced; 2 tablespoons tomato paste; 2 tablespoons medium-dry Sherry; 1 3/4 cups low-sodium fat-free beef broth; 1 1/2 teaspoons salt; 1/4 teaspoon black pepper; Garnish: chopped fresh flat-leaf parsley