Cook potatoes with skins on in boiling salted water until tender. Drain and let cool. Peel potatoes and cut into one-inch chunks.
Heat oil in medium skillet and add onion. Cook until soft and slightly browned. Let cool.
Separate egg whites from the yolks. Set yolks aside. Chop the whites of the eggs and add to potatoes, along with the onion and celery.
In a small bowl, mash the yolks with a fork. Stir in mayonnaise, evaporated milk, vinegar, mustard, sugar, salt and pepper. Pour over potatoes and toss well. Taste and add more salt and pepper if necessary. Divide into serving bowls and garnish with paprika