In a glass bowl, whisk together the mustard, salt, pepper, vinegar, and shallot. Drizzle the olive oil over in a slow, thin stream, whisking all the time until the dressing is emulsified.
In a large bowl, combine the lettuce with enough dressing to coat generously. Place a mound of the salad on each of 6 chilled plates and garnish with some of the diced egg white and a dusting of the sieved yolk.
c.1996, M.S. Milliken & S. Feniger, all rights reserved