Optional: Additional chopped tomatoes and cucumber
In a large skillet, cook beef, onion and garlic over medium heat 8-10 minutes or until beef is no longer pink and vegetables are tender, breaking beef into crumbles; drain. Stir in oregano and 1/2 teaspoon salt.
In a small bowl, mix yogurt, tomato, cucumber, dill and remaining 1/4 tsp. salt. Spoon 3/4 cup beef mixture over each pita bread; top with 3 tablespoons yogurt sauce. If desired, top with additional tomatoes and cucumber. Serve with remaining yogurt sauce.