Eel is best during early Autumn. They live in fresh water for 5~10 years and they swim towards the ocean to lay eggs during this season. It is these eel that taste the best.
Unlike regular fish, fresh water fish smell exceptionally good when they are grilled with soy sauce and sugar. It is known that the amino acid methionine in the soy sauce, sugar, and hypericin in eel create a scent that triggers hunger when they are grilled together.
From the early days, ungai restaurants vented the smoke they created towards the streets to gather customers.
Depending on the season, some eel have bellies with shades of gold, and they where initially called munagi, or yellow chest. This name has been altered to plain ungai after the 1700’s.
Three different preparations of eel exist in Japan. The first is the Tokyo style (thus used for sushi), The Osaka style, and the plain shiroyaki or “white grill”.
The Tokyo style is unique for its steaming involved in the process (please see Eel Sushi), and filleting it from the back.
The Osaka style butterflies the eel from the stomach and keeps the head on. It is then grilled over open flame and then basted with sauce. Grilled eel in Osaka has a firmer flesh than the fragile and flaky Tokyo style. “White Grill” is a simple grill with salt, but it is eaten with wasabi, or grated daikon radish
Specialist unagi restaurants are common in Japan, and commonly have signs showing the word unagi with hiragana, which is the first letter of the word unagi. Lake Hamana in Hamamatsu city, Shizuoka prefecture is considered to be the home of the highest quality unagi; as a result, the lake is surrounded by many small restaurants specializing in various unagi dishes. Unagi is often eaten during the hot summers in Japan. There is even a special day for eating unagi, the midsummer day of the Ox (doyo no ushi no hi).
Unakyu is a common expression used for sushi containing eel & cucumber. Due to the health hazards of eating raw freshwater fish, eels are always cooked, and in Japanese food, are often served with tare sauce. Unagi that is roasted without tare and only seasoned with salt is known as “Shirayaki”.