Heat a large, deep skillet over medium heat; add oil.
Add garlic; sauté 30 seconds. Stir in spinach, and cook 3 minutes or until wilted.
Stir in barley, tomatoes, broth, and salt. Bring to a boil; cover, reduce heat to low, and simmer 20 minutes or until barley is tender. Remove from heat, and stir in mint, green onions, and feta cheese.