1. Peel the potatoes and add to a large pot of boiling salted water.
2. Cook until tender but still firm, about 15 minutes. Drain, cool and cube.
3. Place into a large bowl and set aside.
4. In a double boiler, bring vinegar to a boil.
5. Gradually beat in eggs and cook over simmering water until thickened.
6. Stir in butter and cook 1 minute.
7. Whisk in cream, parsley, onion, mustard, salt, pepper and cayenne.
8. Pour over hot potatoes and combine.
9. Cool, sprinkle with parsley and refrigerate until serving time.

Serves:6 persons
Calories:364