Break or cut pita into 2"/5 cm pieces. Spread on a baking sheet and bake at 400F/200C for 15 minutes or until lightly toasted. Cover red onion with ice water and soak 1/2 hour. Drain well. Wash and dry lettuce well and cut into 2"/5 cm pieces. Combine tomatoes with cucumbers and celery. Toss in olives, cheese and herbs. Combine vinegar with lemon juice, garlic, salt, pepper and whisk in oil. Combine with tomato mixture. About 10 minutes before serving, toss pita bread with onion, lettuce and tomato mixture. Season with salt and pepper to taste. NOTES : This recipe for Middle Eastern Pita Salad makes 6 servings