Preheat a grill pan, large nonstick skillet, or outdoor grill to medium high heat.
In a large bowl combine the ground meat with the yogurt, parsley, garlic, spices, and seasonings. Form 8 3-inch patties. Drizzle the patties with olive oil and cook for approximately 3 minutes on each side in 2 batches. Hold the cooked patties on a plate under foil.
In a large, shallow serving bowl combine the cucumber, bell pepper, celery, red onion, tomatoes, feta, olives, and peperoncini. Dress the salad with lemon juice and salt. Toss, add 3 tablespoons olive oil, and toss again. Taste to adjust seasonings. Top the salad with the patties and serve with pita bread.