Place the porcini mushrooms in a medium bowl; cover with boiling water. Cover and let stand 30 minutes or until tender. Drain mushrooms in a colander over a bowl, reserving liquid. Chop mushrooms; set aside.
Heat a Dutch oven over medium-high heat. Coat pan with cooking spray. Add cremini mushrooms and chopped onion; sauté 10 minutes or until lightly browned. Spoon onion mixture into a medium bowl. Recoat pan with cooking spray. Add chopped carrot, celery, parsnip, and minced garlic; sauté 4 minutes or until lightly browned. Add carrot mixture to onion mixture in a bowl.
Heat oil in pan over medium-high heat. Add beef; cook 3 minutes, browning on all sides. Add 1 cup broth to pan, scraping pan to loosen browned bits. Add remaining 5 cups broth, chopped porcini, porcini liquid, onion mixture, 2 cups water, salt, pepper, and thyme. Bring to a boil; cover, reduce heat to medium-low, and simmer 1 hour or until beef is just tender.
Discard thyme sprigs. Stir in barley; cover and cook 30 minutes or until barley is al dente. Uncover and cook an additional 15 minutes. Remove from heat; sprinkle with parsley.