My Grandmother Sue taught me how to make her Potato Salad when I was not old enough to reach the counter. She was a wonderful cook and loved by all. The greatest compliment my Father ever gave me was that my potato salad taste just like Grandma's!
Cook potatoes in the skins until fork tender in salted water. Let cool till able to handle. Dice potatoes into a large bowl and add to already diced onion, celery and hardboiled eggs. Salt and pepper till desired.
In a medium size sauce pan whisk eggs and sugar. Turn head on medium and add vinegar, water and flour. Whisk until thickened and smooth, whisking constantly. At this point you can add additional flavorings if you want. I sometimes give it a squirt of yellow mustard and about 1/4 cup Miracle Whip or Mayonnaise.
Pour over warm potato mixture and combine well trying not to break up potatoes. The potatoes will take the dressing better if they are still warm. When thoroughly combined, cover and refrigerate.