I love living in Tokyo, though the heat and persistent humidity can try my enthusiasm in the summertime. When temperatures still hover above 30 Celsius (90 F) at the end of the day, lethargy sets in. Natsubaté is what the Japanese call this listless state. And, people here believe the culinary cure for natsubaté is eating eels. Indeed, there is a special mid-summer day devoted to eel-eating, called "doyō no ushi no hi."
EEL-EATING DAYS of SUMMER
Doyō no ushi no hi
"Ushi no hi" (literally, "ox day”) refers to a cycle of 12 animal names assigned to time periods, both years (the next Ox Year will be 2017) as well as days within each year. Many Asian cultures use these names. Doyō refers to the 18-day time period prior to a change of seasons. There is a doyō period before the onset of winter, spring, summer, and autumn. It is this latter one that most Japanese are familiar with, since it is on the ox day of this pre-autumn doyō, that eel-eating is believed to restore stamina that has been sapped by summer heat. And, eel is a truly nutritious food. Rich in vitamins B1 and A, high in EPA (which lowers blood cholesterol) and DHA (sometimes called "brain food," it is thought to enhance mental acumen).
Different Ways of Preparing Eel
Depending upon where in Japan, unagi is processed regional preferences are evident in the preparation of the soy glaze-grilled eel dish known as kabayaki.
In the Kansai region, that includes Osaka and Kyoto, eels are slit ("butterflied") hara-biraki ("belly-split") style (bottom illustration, above), keeping the meat along the back connected. These fillets are threaded on thin, round, metal skewers, before being dipped in a mirin and soy mixture, then glazed and grilled. This results in a richly burnished, intensely flavored eel with fairly crispy skin.
In Tokyo (historically called Edo) and the surrounding Kanto plains area, se-biraki ("back-splitting") is the preferred method of filleting (illustrated on top, above). This technique keeps the meat connected at the belly. Bamboo skewers are threaded through the flesh before steaming the eel. Then the eel is lightly grilled, before being glazed and grilled some more. This produces a leaner, softer textured eel.
In the photo at the very top of this post, belly-split kabayaki is set on a bed of rice in a box; a dish known as unajū. Back-split eel is shown on the right as unadon (eel on a bed of rice in a bowl).
Some culinary professionals say the practice of back-splitting eel (se-biraki) began in Edo eateries not because of taste or texture preferences, but rather to accommodate their samurai customers for whom belly-splitting would be an unpleasant reminder of ritual belly-slitting suicide, seppuku or hara-kiri. Above a drawing of a well-known seppuku scene: Asano Takuminokami of Chūshingura fame fulfilling his samurai duty (Asano's retainers would become the 47 rōnin often depicted in dramas).