1 lb. bacon - fried, crumbled, grease reserved
9 med. potatoes - peeled, sliced, boiled until tender
1 lrg. onion - sliced thin
1/2 cup all-purpose flour
2 1/4 cups water
1 1/4 cups distilled white vinegar
1/2 cup granulated sugar
Toss together crumbled bacon, potatoes, and onion in a bowl; set aside.
Melt bacon grease in saucepan over medium-high heat; stir in flour; slowly whisk in water and vinegar; stir in sugar; continue cooking, stirring constantly, until thickened.
Pour hot mixture over potatoes in the bowl.