Spinach adds a fresh boost to this beefy soup that's just as classic as it is chock-full of flavor.
Combine beef, water, soup mix, thyme, salt and pepper in stockpot; bring to a boil. Reduce heat; cover tightly and simmer 60 minutes.
Stir in barley; bring to a boil. Reduce heat; continue simmering, covered, 45 minutes to 1 hour or until beef is fork-tender and barley is tender. Stir in spinach; cover and remove from heat. Let stand 5 minutes. Season with salt and pepper, if desired.