Boil potatoes with skins on until fork tender, not over cooked. Allow potatoes to cool slightly, slip skins off of potatoes and dice into approximately 3/4 inch cubes or slightly larger. Finely slice or fine dice celery. Grate onion reserving juice as well. In a large bowl, mix together mayonnaise, yellow mustard, grated onion and cayenne, until combined. Add diced potatoes, grated boiled eggs and celery, toss gently so as not to break cubed potatoes, gently to combine. Chill. Flavors will develop. Serve with a sprinkle of paprika if desired. This recipe doubles well.