Preheat oven to 375°F. Line jelly-roll pan with aluminum foil. Coat with nonstick cooking spray.
Combine beef, feta, oregano, mint, allspice in bowl. Shape in prepared pan into 7 x 5 x 1-1/4-inch rectangle.
Bake in preheated 375° F oven for 40 minutes or until juices run clear.
Combine yogurt, garlic, cucumber and salt in a small bowl.
Slice meat thin. Place in pitas with tomatoes. Garnish with mint if desired. Serve with yogurt sauce.
