It's hardly a secret. In fact one of the worlds most renowned chefs, Heston Blumenthal, openly describes the practice.
In the TV series, In Search of Perfection, he goes the extra mile to figure out a way to reproduce the recipe in reasonably well equipped home kitchens. One of the many tricks is that having salt in the blanching water is mandatory. It helps to create the porous surface. His recipe is so good I can make delicious chips at home even without access to a temperature controlled fat fryer.
(Incidentally, Jamie Oliver blanches whole skinned potatoes before roasting them in the oven. I've tried that too and it does make a big difference to how they come up.)
But the vinegar trick was something I hadn't heard before. I'll have to give it a try, because it would seem to give some extra leeway with timing. For a home cook, that is an important factor.
Is that what Jamie Oliver recommends, or is it some further less standard trick?
Just one deviation: steam-dry step instead of putting the lid back on. The potatoes are poured out to a colander and left there for a few minutes.
I'm reading it more as a slow story book. The history of the dishes, their evolution and particularly the failures are fascinating in and of themselves. Some of the nicer ways to cut the difficult corners (or in a way, "cheat") are the only things I can apply in my own cooking. Well... maybe some of the more unexpected flavour combinations might come in handy too. Haven't had the opportunity to try yet.
The main feature are the stories. After the history of any single dish it's interesting to see the final application of the procedures, and just how far the kitchen staff at the Fat Duck are willing to go. (eg. "Store in cool for five days to properly infuse the flavours.")
I have yet to eat at the Duck, though. Maybe sometime next year...
It's so much better to visit the restaurant with some knowledge of Heston's philosophy and the dishes. Having skimmed through the book and watched some of Heston's shows, eating there was much more exciting. If you are interested, [here](http://rafal.io/posts/the-fat-duck.html) is my write-up of my evening there together with some photographs. I definitely recommend you attend. Even though it's very expensive, I always prefer to spend money on experiences I'll remember, such as this one.