The Waldorf salad was created by Oscar Tschirky of the original Waldorf Hotel which later became the Waldorf-Astoria, in the late 1800s. It's quick and easy to make and much of the work can be done in advance.
1/2 c. mayonnaise
1/4 c. sour cream
2 T. fresh lemon juice
2 apples, peeled, cored and cut into into 1/2 inch dice
1 c. celery, very thinly sliced
1 c. red seedless grapes, halved
Boston lettuce leaves
1/2 c. walnut halves
Whisk mayo, sour cream and lemon juice in a large mixing bowl.
Cut apples into 1/2-inch dice; add to the dressing, tossing well to coat. Add celery and grapes; combine well.
Place lettuce leaves on 4-6 salad plates; mound the apples, celery and grapes in the center; top each with walnuts. Serve immediately.
To Make-ahead: The dressing can be made in advance, the fruit and celery cut in advance and the salad assembled when time to serve.