Preheat the oven to 350 degree F. Spread the nuts on a baking sheet and toast in the oven for 8 to 10 minutes. Cool and break the nuts up into small pieces. Half, core, and cut the apples into 3/4-inch pieces, leaving the skin intact. In a medium bowl, mix the apples with the lemon juice, celery, and walnuts.

In a small bowl, whisk together the mayonnaise, chives, sour cream, parsley, sugar, and lemon zest and season with pepper. Add the mayonnaise mixture to the apple mixture and stir to coat. Refrigerate if not using immediately. When ready to serve, arrange the lettuce leaves on a large platter, or divide them among 6 salad plates. Place the salad on the lettuce and serve.