With the rack in the middle position, preheat the oven to 180 °C (350 °F). Line a baking sheet with parchment paper.
In a large bowl, drizzle the oil over the pita bread. Sprinkle with the celery salt and toss to coat. Spread over the baking sheet and toast in the oven for about 12 minutes or until lightly browned. Toss several times during cooking. Let cool completely.
In a bowl, mash the avocado flesh and lemon juice with a fork. Add the remaining ingredients and stir to combine. Season with salt and pepper. Set aside.
In a large serving plate, spread the hummus and sprinkle with the cucumber. Cover with the yogurt and garnish with the avocado, tomato, feta, olives, and celery leaves. Cover and refrigerate until ready to serve. Serve with pita chips.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.