Start by placing the potatoes in a large pot of salted water. Bring to a boil over medium-high heat and cook until tender, about 15-20 minutes.

Once cooked, drain and let them cool at room temperature.

In a large bowl, whisk together the mayonnaise, Dijon mustard, salt, and pepper until thoroughly mixed.

Once the potatoes are cool, chop them into bite-sized pieces.

Add the chopped potatoes to the bowl with the dressing, then fold in the red onion, celery, and chopped boiled eggs.

Gently mix everything together until the potatoes are fully coated with the dressing.

Cover the bowl with plastic wrap and chill in the refrigerator for at least an hour before serving.

Just before serving, sprinkle fresh parsley on top for a pop of color and serve chilled.