To a pot with cold water, add the potatoes and 2 tablespoons salt. Cook until the potatoes are fork-tender, 15 to 20 minutes.
To a food processor, add the yellow onion and celery, pulsing until the vegetables are nice and fine.
Transfer to a large bowl, then add the mayonnaise, scallions, mustard and vinegar. Add the warm potatoes to the dressing; this allows for the potatoes to soak up the flavors of the dressing. While mixing the potatoes in the dressing, gently mash some of the potatoes with the back of a wooden spoon so that they aren’t all in large pieces. Cover and refrigerate for 1 hour or overnight; the longer the potato salad sits in the refrigerator, the better the flavor will be.
Garnish with the scallion tops and serve. |