Steps
1. In a bowl, combine Greek yogurt, Dijon mustard, lemon juice, salt, and pepper to make the dressing.
2. Add shredded chicken, chopped celery, and red onion to the dressing. Mix well.
3. Drizzle olive oil over the lettuce leaf and place it on a plate.
4. Spoon the chicken salad mixture onto the center of the lettuce leaf.
5. Sprinkle chopped walnuts or almonds on top if using.
6. Carefully wrap the lettuce leaf around the filling to create a wrap.
7. Serve immediately as a light main dish.