If you don't have shallots on hand, substitute half an onion, finely minced (use a sweet onion if posible). Thinly slices scallions work too. You can make this salad up to a day ahead and refrigerate it, but it is best served at room temperature. Simply take out of the refrigerator an hour before serving.
Quick tip: If the mayonnaise mixture seems too think, add additional vinegar or fresh lemon juice a few teaspoons at a time until it's just right.
See recipe: New Potato Salad