1. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Combine beef, 1/4 cup parsley, cilantro, and next 5 ingredients in a medium bowl. Divide mixture into 4 equal portions, shaping each into a 1/2-inch-thick patty. Add patties to pan; cook 3 minutes on each side or until desired degree of doneness.
2. Combine cucumber and vinegar in a medium bowl; toss well. Combine yogurt, remaining 2 tablespoons parsley, juice, and pepper in a small bowl; stir with a whisk. Arrange 1 patty and 1/2 cup cucumber mixture on each of 4 plates. Top each serving with about 2 tablespoons yogurt sauce. Serve each with 2 pita wedges.