Mache Salad with Creole Vinaigrette

Mache Salad with Creole Vinaigrette - serves 10

Vinaigrette can be made 1 day ahead and chilled, covered. Bring to room temperature, then whisk until combined well.

Ingredients:
1 yolk from a large hard-boiled egg
2 3/4 teaspoons white-wine vinegar
1 teaspoon Dijon mustard
1/4 teaspoon salt
1/8 teaspoon black pepper
1/4 cup olive oil
16 cups loosely packed mâche (lamb's lettuce; see above)

Directions:
Crumble yolk into a blender, then add vinegar, mustard, salt, and pepper and blend until combined well. With motor running, add oil in a slow stream, blending until combined well.
Toss mâche with vinaigrette just before serving.