Fantasy Veggie Dinner Guest - BASIL FAWLTY

Well there is only one thing it could be! (Sometimes the most obvious is also the best).
According to the American Century Cookbook, the first Waldorf Salad was created in New York City in 1893, by Oscar Tschirky, the maître d’hôtel of the Waldorf Astoria.
The ingredients are familiar to anyone who remembers this classic episode:

Mr Hamilton: Could you make me a Waldorf salad?

Basil: Waldorf salad? I think we're just out of Waldorfs.

Mr Hamilton: I don't believe this.

Mrs Hamilton: It's not very well known here, Harry.

Basil: May I recommend tonight…

Mr Hamilton: I'm sure your chef knows how to fix me a Waldorf salad.

Basil: I wouldn't be too sure.

Mr Hamilton: He's a chef, isn't he?

Basil: You wouldn't prefer…

Mr Hamilton: Find out! Go see if he knows how to fix me a Waldorf salad!

Basil: Of course, yes (later) He's not positive he's almost got it. It's lettuce and tomato…

Mr Hamilton: No, no! It's celery, apples, walnuts, grapes! In a mayonnaise sauce.

Basil: Incidentally, he did ask me to say that he does especially recommend the pâté tonight.

Mr Hamilton: I don't want pâté.

Basil: Or the grapefruit?

Mr Hamilton: The grapefruit? How's it done?

Basil: Well, it's halved, with a cherry in the centre.

Mr Hamilton: Look! I haven't paid you £20 to have some guy cut a grapefruit in half and stick a cherry in the centre!

Basil: Exactly.

Mr Hamilton: I want a Waldorf salad!

Basil: Absolutely.

2 sweet apples, cored and chopped
1 cup/ 120g/ 4½oz seedless grapes, sliced in half
1 cup/ 120g/ 4½oz celery, thinly sliced
1 cup/ 120g/ 4½oz walnuts, chopped and slightly toasted.

and for the sauce, mix together:

6 tbsp mayonnaise
1 tbsp lemon juice
1/2 teaspoon salt

pinch of freshly ground black pepper
N.B. The apples are usually green ones and it is served on a bed of lettuce to keep to one colour.

And the method? Mix all together...