Method1) Prep. Add your potatoes to a pot large enough to cover them fully with water. Add plenty of salt to the water to season the potatoes, and bring the water to a simmer. Simmer until the potatoes are soft enough to pierce through with the tip of a knife or toothpick, and then strain and cool them.2) For the dressing, whisk the vinegar while very slowly adding the oil, whisking until the mixture thickens slightly. Combine the celery, chopped scallions, parsley, eggs, salt and pepper in a large bowl. Pour in the dressing, and toss everything together well until all of the dressing has been absorbed and the salad is thoroughly mixed.3) Taste the salad and adjust the seasonings your taste preference. If you find it too tart, add a pinch of sugar to sweeten it up. Pop the salad into the fridge for an hour to allow the flavors to meld. The salad can even be made a day ahead of time to save prep time on the day of a large cookout.4) Serve. Serve cold or at room temperature.