Today, almost anything thinly sliced gets called "carpaccio"—but the name of this 1950 Harry's Bar creation originally referred to its color: It was named for the great Venetian painter Vittorio Carpaccio, noted for his reds and whites. It was inspired by the Contessa Amalia Nani Mocenigo, a steady customer whose doctor had forbidden her to eat cooked meat.

FOR THE SAUCE:
1 egg yolk
1 tsp. white wine vinegar or red wine vinegar
2 pinches dry mustard
Salt and freshly ground white pepper
3⁄4 cup olive oil
Juice of 1⁄2 lemon
1–2 dashes worcestershire sauce, or to taste
1 1⁄2 tsp. milk
Salt and freshly ground white pepper

FOR THE CARPACCIO:
1 1⁄2 lbs. boned shell of beef, trimmed of all fat, sinew,
   and gristle

1. For the sauce: Make a mayonnaise by putting egg yolk, vinegar, mustard, and a little salt and pepper in a medium mixing bowl and whisking until foamy and thoroughly blended. Add 1⁄4 cup of the oil drop by drop, whisking constantly. Gradually add the rest of the oil in a thin, steady stream, continuing to whisk as the mayonnaise thickens. Add 1 tbsp. of the lemon juice, or to taste, and adjust seasonings, whisking in a little beef or chicken broth (or water) to thin the mayonnaise, if you like.

2. Put 1⁄2 cup mayonnaise (reserve the rest for another use) in a small mixing bowl; whisk in worcestershire and 1⁄4 tsp. of the lemon juice, then enough milk to make a thin sauce that just coats the back of a wooden spoon. Season to taste with salt and pepper, and add a little more worcestershire and/or lemon juice, if you like.

3. To assemble: Make sure the beef is very cold, then slice into the thinnest possible slices, using a razor-sharp, long-bladed slicing knife (see Slicing Carpaccio). It will take several slices before you will be able to get thin, even slices. Divide slices among six small chilled plates, arranging them in one thin layer, covering the surface completely. Drizzle some of the sauce over meat on each plate and serve immediately.