Grilled unagi is a relatively expensive delicacy in Japan, prized not only for its flavor but also for its legendary stamina-giving properties. It's traditionally eaten during the hottest part of the summer (on the "Day of the Ox" on the lunar calendar) to provide strength and vitality for the rest of the year.
Well-prepared unagi combines a rich flavor, a bit like pate, with an appetizing texture, crisp on the outside but succulent and tender on the inside. The cooking process is what makes the eel crisp and tender: The eels are first grilled over hot charcoal, then steamed to remove excess fat, then seasoned with a sweetish sauce and grilled a second time. In the Kansai area (around Osaka) the steaming step is omitted and the eel is grilled longer, burning off the excess fat and producing an even crisper skin.
The ingredients in the sweet basting sauce are important to the final taste of the unagi, and different restaurants maintain their own secret recipes. The quality of the charcoal used is also important: The best charcoal is made from hard oak from Wakayama in central Japan, and the aromatic smoke adds a special flavor to the eel as it's grilling.
As for the eels themselves, the best are caught wild rather than bred in eel farms, with the ideal size between 30 and 50 centimeters. Fancy unagi restaurants keep tanks full of live eels, and they don't begin preparing your eel until after you've ordered. This process requires a bit of time and patience, but you're guaranteed completely fresh eel, and the results ate well worth the wait.
Unagi restaurants can be recognized by an elongated (€) character (the first character in 'unagi'), fashioned to resemble an eel and displayed prominently on the shop sign or curtain.
Grilled unagi on skewers without rice is called kabayaki, and it's often served as an hors d'oeuvre with drinks. This same grilled unagi is also served over a bed of rice as a main course, and this is called unaju or unagi donburi, depending on the shape of the serving dish.
Eel grilled without sauce is called shirayaki. This plain form of eel is most popular with diehard unagi purists. When you order a full-course eel meal you'll be served kimosui, a clear soup made from eel livers. The livers themselves are very nutritious, although not everyone enjoys the taste.
At the table you may lightly sprinkle your unagi with sansho, an aromatic Japanese pepper whose powdered form is most often found on unagi-restaurant tables.
Other specialty fish - dojo, anago, hamo, anko
Some unagi restaurants also serve dojo (called loach or dojo loach in English). The dojo is a small freshwater eel-like fish related to the carp, and it is caught in local waters in the summer. Some restaurants specialize in dojo, while others concentrate their.efforts on unagi. The best known dojo dish is yanagawa-nabe, a mild casserole made with boiled dojo, burdock root, and eggs.
Anago (conger eel) is best known as a sushi-counter standard, where it is grilled and brushed with a sweet sauce before being set atop a finger of rice. There are also a few upscale anago specialty restaurants that prepare the fish in various styles - sashimi, grilled with or without sauce, fried tempura-style, and served over rice as anago-meshi.
Hamo (pike eel or pike conger eel), a hardy sea eel, is a summertime favorite in Kyoto, although it's not often found in Tokyo. It is served in traditional Kyoto-cuisine restaurants and in hamo specialty restaurants.
Anko (monkfish or anglerfish) is another fish that has inspired its own set of expensive specialty restaurants. Ankimo (steamed anko liver) is a famous Japanese delicacy, and it is often compared to foie gras because of its rich flavor. The fish itself is generally prepared as anko-nabe (anko stew).