Source: The Luchow book published in 1952

1 pound (3 medium) potatoes
6 slices bacon, diced
1 medium size onion, diced
1/2 cup vinegar
1/2 cup stock or bouillon
1 teaspoon salt
1/4 teaspoon pepper
1 teaspoon granulated sugar
1 egg yolk, beaten

Scrub potatoes; rinse. Boil in jackets; let cool. Peel and cut in 1/4-inch slices.

Cook bacon in hot pan until crisp. Add onion; stir and cook until transparent. Add vinegar, stock or bouillon, and seasonings. Stir; let come to a boil. Stir in egg; remove from heat and pour over potatoes.

Serves 2-4.