My Dad's Deli-Style Potato Salad

from ButterYum
makes 5 pounds

5 pounds white or red new potatoes, cut into 1-inch cubes
8 cups water
1 teaspoon kosher salt

2 cups mayonnaise (we love Duke's)
1/4 cup white distilled vinegar
1 teaspoon kosher salt
1/2 teaspoon ground black pepper
1 cup finely minced onion
option garnish:  chopped parsley, chives, scallions, etc

Place the cubed potatoes in a 6-quart stockpot, add water and 1 teaspoon of kosher salt; bring to a boil and cook until fork tender.  Drain and cool potatoes completely.  In a large bowl, whisk together mayonnaise, vinegar, onion, salt, and pepper.  Pour over cooled potatoes; gently mix and garnish if desired.  Refrigerate leftovers.