Peel and chop potatoes into 1-inch pieces.
Place the potatoes into a deep pot, and cover with water. Add a heaping teaspoon of salt to the pot and bring the potatoes to a boil. Cook until potatoes are tender. Drain and rinse with cold water until completely cool.
Place potatoes, celery, eggs, and onion in a large salad bowl.
In a separate bowl, whisk together mayonnaise, sugar, vinegar, and yellow mustard.
Pour dressing mixture over the ingredients in the salad bowl.
Toss until fully combined.
Chill for at least one hour before serving.
