Grandma’s Easy 12-Hour Potato Salad

Boil (whole) potatoes until soft; a knife should be able to be inserted easily, about 45 minutes. Drain potatoes and let cool 20 minutes or so. In a large bowl, combine water, vinegar, salt, pepper, sugar, parsley, onion and celery together. Set aside. Peel warm potatoes (skin should come off really easily using a butter knife or spoon), cut into large cubes and place into the vinegar mixture in the bowl. Stir to coat warm potatoes in marinating liquid. Cover and refrigerate at least 12 hours (up to 24 hours). Before serving, stir in mayonnaise (you can add less or more to your discretion). Keep cool until ready to serve.