1Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally, until cooked through but firm to the bite, 8 minutes; drain. Rinse with cold water until cool; drain.
2Chop egg whites; toss in a bowl with the macaroni, celery, sweet onion, and shredded carrot.
3Blend egg yolks, mayonnaise, mustard, vinegar, milk, sugar, and salt in a blender until smooth; pour over the macaroni mixture and stir to coat.