Hot German Potato Salad

This recipe belonged to my Grandmother, on my mom’s side. It is the only potato salad recipe my sister would touch.
2 med potatoes
3/4 tsp salt
3 slices bacon
1/4 tsp celery seeds
1/2 cup chopped onion
dash pepper
1 tbsp flour
1/3 c water
2-3 tsp sugar
3 tbsp vinegar

Boil potatoes in jackets. Peel and slice thinly. Fry bacon, drain and crumble. Saute onion in bacon drippings until golden brown. Blend in flour and seasonings. Cook over low heat, stirring until smooth and bubbly. Remove from heat. Stir in water and vinegar. Bring to boil, stirring constantly. Boil 1 min. Stir in potatoes and crumbled bacon, gently. Remove from heat, cover, let stand until ready to serve.