1. Rinse the pearl barley and black barley in two separate strainers under cold running water for 5 minutes. Pat dry and keep separate. Fill two separate pots with 1 quart salted water. Add the black barley to one and cook for 1 hour and 15 minutes. Add the pearl barley to the other and cook for 45 minutes, or according to the directions on the package. Strain each and set aside.
2. Heat 2 tablespoons of the olive oil in a large saute pan over medium heat. Add the garlic, pine nuts, and jalapefio and saute until fragrant, about 3 minutes. Add the spinach and za'atar and cook until the spinach has wilted, 3 to 4 minutes.
3. Combine the remaining olive oil, the pearl barley, black barley, spinach mixture, tomatoes, scallions, lime juice, parsley, feta, cucumber, onion, vinegar, olives, and mint in a large bowl. Season with salt and pepper.