In a medium saucepan bring about 3 cups of water to a boil over high heat. Rinse barley and add it to the pot. Reduce heat to medium-low. Partially cover and cook for 20 - 25 minutes until the barley is tender but still chewy. Drain and rinse barley and set aside. Note: the barley can be cooked ahead and refrigerated.

Meanwhile, in a 5 qt Dutch oven, heat about 1 teaspoon of the oil over medium-high heat. Add half of the beef cubes and brown on all sides; with a slotted spoon remove them to a plate. Add about another 1 teaspoon of oil and repeat process with remaining beef. Set aside.

Add remaining olive oil to the Dutch oven. Add onion, carrots, celery, green beans and potatoes and cook over medium-high heat for two minutes, while stirring constantly.

Add diced tomatoes, tomato paste, beef broth, water, balsamic vinegar, bay leaf, oregano and cooked barley. Return browned beef and any accumulated juices to the Dutch oven. Season with salt and pepper.

Cook uncovered on medium-high heat until soup comes to a light boil, let bubble for 5 minutes. Reduce heat to low, cover and simmer for 30 minutes until the vegetables and barley are completely tender.