In 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 up beef into crumbles; drain. Stir in oregano and 1/2 tsp (2 mL) salt.
In small bowl, mix yogurt, tomato, cucumber, dill, and remaining salt. Spoon 3/4 cup (175 mL) beef mixture over each pita bread; top with 3 tbsp (45 mL) yogurt sauce. If desired, top with additional tomatoes and cucumbers. Serve with remaining yogurt sauce.