In a small saucepan combine onion, vinegar and sugar. Bring to a simmer, stirring occasionally. Remove from heat; set aside.
Meanwhile, cook macaroni according to package directions. Drain and rinse well with cold water; set aside.
Coarsely chop one egg; set aside. Halve remaining eggs; separate yolks from whites. Coarsely chop egg whites; set aside.
For dressing, place yolks in a medium bowl; mash with a fork. Add mayonnaise, mustard, and onion and vinegar mixture. Gradually stir in 2 Tbsp. water, salt, paprika, and pepper. Set aside.
In a large bowl combine the egg whites, pickles, celery, macaroni, and dressing; toss to combine. Top with reserved egg; sprinkle with additional smoked paprika and pepper. Serve at once or cover and chill up to 6 hours.
If the mixture gets a little dry after storing, you can stir in a little milk.