In a small saucepan, combine white vinegar, sugar, salt, water, and ground white pepper. Heat to boiling and pour immediately over the sliced potatoes and onion, mixing lightly with a rubber spatula.

Cover and marinate for 2 hours in refrigerator. Blend in oil and mayonnaise until creamy, mixing very well.

Note: For German style, add crisped bacon bits and a little of the bacon fat instead of mayonnaise. You may also with to add more vinegar to taste.