1Microwave or boil the water, vinegar, sugar and salt. Make sure the sugar and salt are stirred well.
2Peel the potatoes and thinly slice. Place in a large bowl or casserole dish. Spread the 2 tbs of oil over the potatoes and gently cover all the potatoes. Gently mix in the chopped onion.
3Add enough boiled liquid to the potatoes and onion mixture gently covering all the potatoes. Depending on the amount of potatoes, all the liquid might not be necessary. Potato salad should be moist but not saturated. Sprinkle with white pepper.
Can be eaten warm (German). Refrigerate and add 2 tbs mayo after cooling (American).