This is my friend Ruth's recipe...she's not German, but she's Czechoslovakian, which is close enough.
Baked German Potato Salad
1 cup diced bacon
1 cup chopped celery
1 cup chopped onions
3 tbsp flour
1 tsp salt
1/2 tsp pepper
2/3 cup sugar (I use less)
2/3 cup cider vinegar
1-1/2 cups water
1/3 cup fresh chopped celery
2 tsp celery seed
2 quarts red potatoes, boiled, peeled (or not,)sliced 1/8 inch thick
Fry bacon, and save 1/4 cup grease. Add vegetable oil if necessary to make ¼ cup. Remove bacon and add onion and celery to oil.
Cook 3 minutes, add flour, salt and pepper and cook 2 min more. Then add sugar, vinegar and water stir with whisk bring to a boil and cook 1 minute.
Add parsley, celery seed and reserved bacon and combine. Remove from heat.
Pre-heat oven to 375. Place potatoes in oiled 13x8x2 in casserole dish and pour dressing over all. Mix gently so potatoes don’t break up. Bake 45 minutes, or until middle of casserole bubbles.
We get by with a little help from our friends