My Prussian grandmother made warm potato salad on this wise: 5# small red potatoes, boiled until tender, drained and left out overnight. Peeled and sliced into rounds, and layered with five stalks of celery diced and three bunches of spring onions, sliced (leaving about three inches of green at the ends), and one pound of bacon, fried crisp, crumbled; bacon drippings reserved in the pan. Layer potatoes, celery, bacon and onions. To the very warm bacon drippings add one pint white vinegar mixed well with two cups sugar, one tsp salt, one tsp pepper. Deglaze pan of hot bacon drippings wih this mixture, and allow to cook until a roiling bubbling is reached, mix a little flour to thicken, continue to cook over medium heat until the mixture is very thick and hot - adjust vinegar/sugar to taste while still cooking, and when the proper tart-sweet mix is reached, pour over the potatoes. Serve immediately.