This is a traditional, inexpensive bistro first course. If you can boil an egg, this recipe is simple! Be sure the eggs are very cold before cutting them in half./This recipe makes enough mayonnaise for 15 to 25 portions, depending on how much is used for each portion.
Prepare the mayonnaise: mix the egg yolk, mustard, vinegar, salt, and pepper together with a whisk. Slowly whisk in the oil, starting with just a few drops until it is completely emulsified. Set aside.
Arrange the salad greens on serving plates. If desired, mix the greens with a light vinaigrette first. Cut each egg in half, lengthwise, and place two halves on each plate. Top each half with some mayonnaise. Garnish with parsley.