6 med. to lg. potatoes
1/2 c. beef or chicken stock
1/2 med. onion, chopped

DRESSING:

6 tbsp. wine vinegar
6 tbsp. olive oil
1 tsp. salt
1/2 tsp. ground pepper
1 egg yolk

Boil potatoes in jackets until tender. Let cool enough to peel and slice. Pour the beef or chicken stock over the potatoes. Add chopped onion. Mix remaining ingredients together and beat until smooth. Pour mixture over potatoes and stir. May be serve warm or cold.