Summer is not the time for a hot German-style potato salad, but right about now I don't think you can beat it. If you are serving something on the rich side, like pork or a roast chicken, hot potato salad is a surprise comfort food that will kick it up a notch, as Emeril Lagasse says.
On the question of bacon, I buy pre-cooked bacon at Sprouts, where they sell bacon of a high quality. All you have to do is crisp it up in a skillet and then remove it to an ingredient bowl after you break it into pieces. Augment what little bacon grease remains in the skillet with olive oil and you will improve the nutrition a bit. I continue to think of bacon as a garnish or ingredient rather than a main dish, no matter what the plump, shiny and trendy chefs seem to think of it.
Cider vinegar provides a gentler acid component than white distilled vinegar, and I prefer it although some people of German ancestry prefer the stronger acid of the white vinegar. My mother customarily cooked with cider vinegar all the time, so I tend to reach for it.
If you read the labels on the mustard jars, you can get some German-style mustard, which is often made with a chunky texture and gives a nice appearance to the potato salad, like the brand Rhinegeld. That is what I would use--this is not the occasion for French Dijon.
You will also want to use "new potatoes," whether they have red, white or Yukon Gold skins. Of course the red potatoes add color to the salad, and if you use them, keep your eye on them as they cook so that they do not fade to a dull brown but keep as much color as they can.
GERMAN-STYLE HOT POTATO SALAD
5 slices bacon, diced and cooked until crisp
1 tablespoon bacon drippings
1/4 cup olive oil
1-1/2 Tablespoons all-purpose flour
1 Tablespoon granulated sugar
1 teaspoon sea salt
1 Tablespoon prepared mustard
1/2 cup cider vinegar
1/2 cup water
4 cups sliced cooked potato
Crisp the bacon in a skillet; remove it from the heat, break it into pieces and set aside.
Heat the olive oil with the bacon drippings; blend in the flour, sugar, salt and mustard. Gradually add the vinegar and water, stirring constantly until smooth.
Cook over low heat, stirring, until thickened. Add the potatoes and heat through, gently stirring to mix. Sprinkle with the reserved bacon.