From Food to Live By: The Earthbound Farm Organic Cookbook by Myra Goodman
thin-skinned potatoes, preferably fingerling (cut into 1/2-inch chunks)
red wine vinegar
extra-virgin olive oil
Salt and freshly ground black pepper
mayonnaise (or more to taste)
minced fresh dill
minced fresh Italian flat leaf parsley
scallions (including white and about 3 inches of green, trimmed and sliced thin (about 3/4 cup))
Place the potatoes in a steamer basket set over a large saucepan filled with about 1/2 inch of boiling water. Steam the potatoes over medium-high heat, covered, until they are tender when pierced with the tip of a knife, 10 to 15 minutes.
Meanwhile, place the mustard, vinegar, olive oil, and 1/2 teaspoon of salt in a glass jar and seal the lid tightly. Shake the jar vigorously to combine. Taste the vinaigrette for seasonings, adding pepper to taste and more salt as needed.
Drain the potatoes in a colander and transfer them to a large bowl. Add 1/4 cup of the vinaigrette and toss to coat the warm potatoes. Let the potatoes cool, and set the remaining vinaigrette aside.
When the potatoes have cooled to room temperature, add the mayonnaise and stir to combine. If the salad seems too dry, stir in some of the remaining vinaigrette. Add the dill, parsley, celery, and scallions, and stir to combine.
Refrigerate the salad, covered, for at least 2 hours before serving for the flavors to develop. It can be refrigerated for up to 3 days. Serve chilled.