Heat 1 tablespoon of olive oil in a large Dutch oven over medium-high heat. Add the beef in batches and cook for 2-3 minutes, or until caramelized. Once the beef is cooked, add the onion and garlic and cook for an additional 2-3 minutes, stirring often.
Add the beef broth and bay leaves, and season with sea salt and freshly cracked pepper, to taste. Cover the Dutch oven with a lid and place it into the oven for 2-3 hours.
Heat the remaining tablespoon of olive oil in a large skillet over medium-high heat. Add the mushrooms and cook for 3-4 minutes until golden brown.
Add the mushrooms, carrots, celery, fingerling potatoes, and pearled barley to the beef soup. Cover and cook on the stovetop over medium-low heat for 45-60 minutes or until the vegetables are soft and the pearled barley is cooked through.
Mix a bit of cornstarch with some cold water and stir until completely dissolved. Add the cornstarch slurry to the boiling soup and stir. Remove from the heat and serve. Enjoy.