IRMA ROMBAUER'S CLASSIC POTATO SALAD

Steps:

• Cut the potatoes in half if large, put in a pot and add enough lightly salted water to cover them by 2 inches. Bring to a boil and cook, uncovered, until just tender, about 15 minutes. Drain. Peel and cut into cubes or slices.
• Put warm potato pieces in a serving bowl and mix with broth. Let stand for 30 minutes so broth can be absorbed.
• Mix in celery, scallions and eggs. Add optional ingredients. Add salt, pepper and cayenne to taste.
• To make the dressing, in the top of a double boiler, mix the egg and cider vinegar. In a small bowl, mix the dry mustard, sugar, salt, flour and paprika. Gradually blend in the cold water until smooth. Whisk into the egg and vinegar mix.
• Cook over boiling water, stirring with a whisk until the dressing is thick and smooth, about 3 minutes. Remove from the heat and whisk in butter. Let cool slightly and thin with sour cream, yogurt or cream if desired. Mix well with potatoes and adjust seasonings. Serve immediately or cover and chill overnight.