Cook potatoes in plenty of boiling salted water until a little more than fork-tender. Drain well. Peel as soon as you can handle them using a towel to hold the hot potato. The peeling should come off easy using a knife to gently scrape off the peel.
While the potatoes are cooking, boil the eggs in salted water. Start timing as soon as water comes to a boil. Cook exactly 12 minutes. Drain and cool under running cold water until cool enough to peel. Peeling under cold water makes the shell come off easier.
In a large bowl, put the still hot potatoes and run through them with a knife going in all directions to make tiny dices. Don't be afraid to chop them well. Add celery, onions and relish. Stir well.
Add mayonnaise, mustard, salt, pepper and garlic powder. Mix well. Add peeled eggs that have been chopped fine. Stir in gently.
Taste and adjust seasoning, if needed. This salad should be on the dry side, not too mushy from mayonnaise. Mr Ed. doesn't measure anything since he's been making this potato salad for more than 50 years. You may want to add half the mayonnaise and then more to get the right consistency or even add more, if needed.
Once you're satisfied with the salad, cover with plastic wrap, leaving a small vent and refrigerate until thoroughly chilled.
Note: Mr Ed chops the eggs in the bowl with the potatoes with a chef's knife.