2 pounds (approx) red potatoes (or Yukon Gold) - washed, cubed & boiled until tender
4 hard boiled eggs, diced
1/2 cup red onion, chopped (about 1 medium onion or 1/2 large)
1 - 1 1/2 cups celery, chopped (2-4 stalks - I like more, my hubby likes less)
1 cup + 1 Tblsp. mayonnaise
1 Tblsp. white vinegar
1 Tblsp. yellow mustard
salt & pepper to taste
Place eggs in a saucepan, cover with cold water and bring to a rolling boil. Remove from heat & set aside (don't drain!), lid on, for 20 minutes. Drain, run cold water over cooked eggs for 1 minute. Move eggs to a towel or rack to cool.
Bring a large pot of water to a boil. Wash & dice about 2 lbs. red potatoes or Yukon Gold potatoes.
Dump diced potatoes into boiling water (watch out for splashes - ouch!). Cook until fork-tender. Drain & set aside to cool.
Wash & dice celery stalks. Dice red onion. Place both in a medium-sized bowl. Add mayonnaise, mustard, & vinegar.
Stir well to combine. (Cover bowl with plastic wrap & place in the refrigerator if your potatoes & eggs aren't cooled yet. You can prepare the onion/celery/mayo mixture the night before, if you want)
Dice the cooled eggs & add to cooled potatoes in a serving bowl. Sprinkle on about 1/2 tsp. pepper & 1/2 tsp. salt. (You might add it plus more later, after you've mixed everything. It's to taste so it's up to you.)
Pour celery/onion/mayo mixture over the potatoes & eggs. Mix well, until all the potatoes are covered with the mayo mixture.