Kyushu (especially Nagasaki) is the epicenter for this dish, but it has spread to many parts of Japan.
There are specialty restaurants that sometimes require a 2 day ahead reservation, as the dish requires at least that long when best prepared.
Question: Have you found a place that does it perfectly, and if so, would you be willing to talk to the chef to share the secrets of the several stages of its preparation?
We have a thread going on the HomeCooking Board, which may serve to hone your questions for the chef, and we'd appreciate your feedback. Questions about the use of Nuka and Daikon and the method of final braising (drop lid?) and/or initial browning are some of the areas of focus. If you have tips on techniques, would you be kind enough to post them there?
I first had the dish at a restaurant in Nagasaki, years ago, and was astounded.