Pat the beef cubes dry with a paper towel and season with salt.
Heat one tablespoon of the oil in a large Dutch oven over medium-high heat and sear the beef cubes on all sides, working in batches so as to not overcrowd. Use a slotted spoon to remove the beef and set aside.
Heat the remaining tablespoons of olive oil and add the onion, carrot and celery to the Dutch oven. Cook for 5 minutes. Add the mushrooms, spinach, garlic and herbs and cook for another minute. Return the beef to the pot and add the wine, beef broth, tomato paste, bay leaf, salt and stir to combine.
Two cooking methods: Preheat the oven to 450 degrees F. Cover the Dutch oven and cook on the lowest rack for 40 minutes OR bring to a boil on the stove top, cover, reduce the heat to low, and simmer for an hour.
While the stew is cooking, add the barley to the water in a medium pot, bring to a boil, reduce the heat to medium, and cook for 10 minutes or until tender. Drain.
Add the barley to the stew and continue to cook for at least 10 more minutes, preferably up to an hour. The longer the stew cooks the more tender the beef and flavorful the stew will be. Add salt and pepper to taste.