Bring eggs up to a boil quickly, turn down burner and steep for 10 minutes.
Cool, peal, chop, and reserve.
Cut celery and onion and reserve.
Cut potatoes into ¾ inch pieces, they do not need to be exact, and place in pot and cover with water. Add in 3 tablespoons of salt and bring up to a boil. Turn burner down to low and steep for 10-15 minutes or until tender. Drain, and allow to cool.
In large mixing bowl combine mayonnaise, mustard, seasoning, chopped egg, celery, and onion and mix until combined.
Add in potatoes and mix to coat. Refrigerate until cool.