2½ pounds small boiling potatoes (white or red)
3 tablespoons cider vinegar, or to taste
5 hard-boiled large eggs
1/8 cup mayonnaise
2 tablespoons Dijon mustard
½ cup chopped sweet onion
3 large celery ribs, chopped

In a large saucepan cover potatoes with salted cold water by 1 inch and
simmer, covered, until just tender, about 15 to 30 minutes, depending on
size of potatoes. In a colander drain potatoes and cool to warm.

With a sharp knife peel warm potatoes and cut into 1/3-inch-thick slices.
In a bowl immediately toss potatoes with vinegar. In a bowl mash egg
yolks and stir in mayonnaise, mustard, and onion. Chop egg whites and
celery and gently toss together with potatoes and mayonnaise mixture.
Salt and pepper to taste. Serve potato salad chilled or at room
temperature.