When I was little, Mother & I would go to downtown Milwaukee to Schuster's Department store on the trolly....yes, the trolly! We would shop and get ring bologna and their famous German Potato salad to have for our dinner. Years later someone in the family was given what was supposed to be their recipe for the salad. I've tinkered with it, and this is the final result. My family and friends say it is better than any other they have ever had...anywhere, anytime!
Saute bacon over medium heat until crisp. Do not allow to get too brown, but be sure to cook through; remove from pan and drain on paper towels.
Saute whites of the onion in the bacon drippings until almost clear & limp; add green and saute a few more minutes, checking to be sure they don't become brown; remove from pan and add to paper towel to drain.
Heat sugar, vinegar and water to a boil. Remove from heat; stir in dissolved cornstarch. Return to medium low heat. Add bacon & onion. Gently stir to combine.
Place still warm, sliced potatoes in buttered oven proof casserole dish (recommendation: 4 qt casserole); Add hot sauce to the mix and gently stir to combine well. Garnish with chopped parsley. Bake at 350 for 45 minutes or until bubbly.
You can make the day before and refrigerate without baking. Be sure to remove casserole from refrigerator and allow to come to room temperature before placing in the oven.