2 pounds waxy potatoes, such as red-skinned or new potatoes, scrubbed
2 large eggs
1 cup mayonnaise
1 celery stalk, small dice (about 1/2 cup)
1/4 cup whole-grain Dijon mustard
1/4 cup dill relish
1/3 cup scallions (from about 1/2 bunch), thinly sliced (white and light green parts only)
2 tablespoons capers, drained
2 tablespoons finely chopped fresh Italian parsley leaves
1 tablespoon freshly squeezed lemon juice (from about 1/2 lemon)
1/2 teaspoon kosher salt, plus more for salting the cooking water
1/8 teaspoon freshly ground black pepper
1Place the potatoes and eggs in a large pot filled with heavily salted water and bring to a boil over high heat. Reduce the heat to medium and simmer until the eggs are hard-boiled, about 12 minutes. Remove the eggs to a medium bowl and place them in the sink. Run cold water over the eggs until they’re cool enough to handle; set aside.
2Continue to simmer the potatoes until a paring knife can easily be inserted, about 5 minutes more. Drain the potatoes in a colander in the sink and allow them to cool slightly, about 10 minutes. Transfer the potatoes to a baking sheet or large plate and arrange them in a single layer. Place the eggs next to the potatoes on the baking sheet and refrigerate everything until completely cooled, about 1 hour. Meanwhile, place the remaining ingredients in a large bowl and stir to combine; refrigerate until you’re ready to finish assembling the salad.
3When the eggs and potatoes have cooled, peel the eggs and grate them on the large holes of a box grater over the bowl with the mayonnaise mixture; set aside.
4Remove the skin from the cooled potatoes with your hands or a paring knife. (For a more rustic potato salad, you can leave the skins on.) Using your hands, break the potatoes into large chunks (about 3/4-inch pieces) and add them to the bowl with the eggs and mayonnaise mixture. Using a rubber spatula, gently fold the potatoes and eggs into the mayonnaise mixture until evenly combined and well-coated. Serve immediately or refrigerate in an airtight container for up to 4 days.