But then, during a trip to Germany, my son asked my mother to make potato salad for dinner - about 30 minutes before dinner was to take place. I figured that it could not be done.
Apparently, my mother disagreed. She pulled out some boiled potatoes from the day before from the fridge and fixed German potato salad in about 10 minutes flat. At dinner, my son remarked: "Mom, Oma's potato salad is still better than yours!" Back in the US I worked on improving my recipe - and I do think it's much better now, if I do say so myself.
So, without further ado, here is the recipe I use now:
The original recipe is from my Dr. Oetker Kochbuch, but like most cooks I know, I only use the recipe as a first approximation. Note that the recipe calls for salad potatoes. I use whatever I have in the kitchen, but I believe that my mother prefers Yukon Gold potatoes for potato salad.
If I have boiled potatoes in the fridge, I use them, because - as I know now - that works, too.
Once the potatoes are cooked, they need to be peeled and sliced. The hotter the potatoes are, the easier it is to peel them. Colder potatoes are less likely to fall apart. It's up to you to err in one direction or another.
The secret ingredient in German Potato salad is bouillon - and, as it turns out, the selection of the bouillon is not trivial:
Beef bouillon is actually something I used to import from Germany. I used any German brand of "Klare Fleischsuppe" (=bouillon), because they all work fine. However, it is now illegal to import beef bouillon from Germany to the US due to fears about BSE so I had to come up with an alternative. [Update May 2016 - The US has dropped the restriction on the import of canned beef products and beef bouillon for the time being. Check the current restrictions before you travel.]
I would advise against using the logical replacement: US produced beef bouillon. For some reason, the manufacturers of US beef bouillon are under the impression that beef bouillon has to be brown. This is even true for the US version of Knorr or Maggi brand. (The German version is essentially clear.) As a result, if you use US beef bouillon, your potato salad will have a reddish brown color - and that's just not a good look for a potato salad.
So instead, I now use vegetable bouillon, either from the US or from Germany. It affects the taste just a little bit, but it's still very good. Some Germans actually make potato salad with vegetable bouillon to start with, so it's still authentic, too.
Boil the bouillon of your choice in water. Then let most of the water boil off so that the bouillon is is quite strong - double or triple strength - according to taste. It is supposed to impart lots of flavor but relatively little liquid. Careful, watch that pot! It's a pain to clean, if you boil all the liquid off and burn it.
My Mom's potato salad has onions in it. When I make this salad for my children, I leave out the onions, because they don't like them. I like onions, but sometimes they give me a headache. One of the tricks I learned from my mother was to salt the cut up onions and actually store them as salted onions in the fridge. The salt takes away some of the onion's bite and brings out more of the sweetness. If you don't like the taste of raw onions, you may want to try to salt them before you put them on a salad, for example.
The dressing consist of 1 part each bouillon, vinegar and oil. I usually add one cup (1/3 cup vinegar, 1/3 cup bouillon and 1/3 cup oil) of the mixture at a time to the potatoes. Let the potatoes sit for a little, if you have the time - if not, just keep adding to taste. For 5 lb of Yukon potatoes I use about 1 cup of each (yes, that's 3 cups of salad dressing). If you use that much, the potatoes will initially sit in liquid. However, if you let the potato salad sit for about an hour - gently mixing it once or twice during that time - all of the liquid will soak into the potatoes. I often shorten the amount of oil a bit and replace it with more bouillon. In the end, I adjust to taste with more bouillon and vinegar as needed.
PS: My kids prefer this warm. Also, if there are leftovers, this tastes good pan fried the next morning.