Steps
1. Wash and dry the lettuce leaf carefully to keep it intact.
2. In a bowl, combine shredded chicken, Greek yogurt, Dijon mustard, chopped celery, and walnuts.
3. Add salt, pepper, and lemon juice to taste, mixing well.
4. Spoon the chicken salad mixture onto the center of the lettuce leaf.
5. Garnish with fresh parsley.
6. Fold the lettuce leaf around the filling and enjoy immediately.