3.Whisk the yogurt, mayonnaise, parsley, honey, and lemon zest in a large bowl and season generously with pepper.
4.Halve, core, and cut the apples into 3/4-inch pieces, leaving the skin intact. Add the apples, celery and raisins to the bowl, and sprinkle with the lemon juice; then toss with the dressing. Cover and refrigerate if not serving immediately.
5.When ready to serve, toss walnuts into the salad. Arrange the lettuce leaves on a large platter, or divide them among 4 salad plates. Place the salad on the lettuce and serve.