There's a common bacon fat vinaigrette served over a wilted spinach salad.
The bacon fat potato salad dressing I use is a Southern German/Northern Austria style dish. Perhaps more of a "gravy" as this one uses a roux.
For 6 cups cooked sliced potatoes still hot:
6 strips of bacon (though I've been using less--4--the last few years)
1/2 cup chopped onion
2 tablespoons flour
2 tablespoons sugar
1 teaspoon salt or to taste
1 teaspoon celery seed
black pepper to taste
1/2 cup vinegar (white is traditional, but I've trended to cider vinegar recently)
1/2 -1 cup reserved potato water. I like it at the 1/2 cup of added water, but the original recipe used a thinner dressing.
Cook 3 strips of bacon, reserve a few tablespoons of drippings. In the same pan as you cooked the bacon, cook the onions in the reserved baking fat until softened and translucent, about 5 minutes.
Add the flour. Stir and cook to form a roux. Add the reserved potato water, vinegar and seasoning, stirring to form a dressing. Stir in the bacon and hot potatoes stir, taste, correct and serve. Best immediately. Reheat any leftovers before serving.