Cook barley in 6 - 8 cups boiling water for 30 minutes; it should be tender but still have some bite to it. Drain and reserve for later. Cut the tops of the peppers measuring a 1/2 inch down from the bottom of the stem. Discard stem but chop up any scrap pepper and reserve for later. Clean peppers of seeds and ribs. Spray a large skillet with cooking spray; add onions, garlic, and reserved chopped peppers. Cook until tender. Add ground turkey, sauté until cooked through. Add cooked barley, raisins, mint, cinnamon, and lemon juice. Combine and cook for a minute or so until spices are aromatic and remove from heat. Fold in yogurt and season to taste with pepper.