Large fishing vessels sail the Pacific Ocean year-round in pursuit of bonito (Skipjack tuna). The fishing method is divided into pole-and-line fishing and purse seine fishing. Pole-and-line fishing involves spreading live bait such as Japanese anchovy to attract schools of skipjack tuna, which are then caught in large numbers with the rod in a short period. Because of the need to keep live bait for a long period, this fishing method was limited to the waters around Japan for many years. Still, recent technological advances have also made pole-and-line fishing possible in southern waters.
The bonito caught in the waters around Japan is called Higashi-no-mono. This follows sardines and other fish that serve as bait and come north from the waters around the Philippines. The bonito called Nanpo-mono also approaches the waters around Japan from off Micronesia and other areas. This one is mainly caught by large vessel purse seine fishing. In purse seine fishing, the bonito rub against each other before being hauled on board, easily damaging the flesh. As a result, the fish may be less fresh and damaged than when caught pole-and-line fishing.
Vessels that take skipjack are equipped with sophisticated refrigeration facilities. There is a pool of brine solution, a salt solution with a concentration of about 20%, on board. The flash-frozen skipjack is called B1. After being thawed and filleted, the fish is rigor mortis, which means it is extremely fresh and is distributed as high-quality frozen skipjack for raw consumption. Of course, they are also very expensive. In addition, when caught, the blood is removed and the fish is flash-frozen, called S1, and is distributed as a higher quality product than B1.
Only carefully selected skipjack and those frozen under strict freezing conditions are marketed as B1, while skipjack that is frozen in the same freezer but not according to B1 standards is distinguished from B1 and referred to as B. Incidentally, B1 and B are caught by pole-and-line fishing. There is another type of frozen bonito called PS. This is not caught by pole-and-line fishing but by purse seine fishing. It is not in as good condition as pole-and-line fishing, but it is handled with care and has few scratches.
In summary, Bonito (skipjack) originally deteriorated quickly and was difficult to distribute fresh, but improvements in freezing technology and other factors have ensured that the quality is close to fresh.
It’s won’t hurt you to eat Magaki (Japanese oyster), which has its spawning season in the summer, but in the months with no R in the name, the glycogen concentration is low, so you can’t get the full-bodied texture that you get in winter. In addition, almost all amino acids such as glutamic acid, glycine, alanine, arginine, which are important components for delicious flavor, are known to accumulate from winter through spring, and conversely, they decrease in the summer, which is the spawning season. You cannot expect the same deliciousness from oysters in summer as you can from months that contain the letter R.
Naturally, the cost price is what it costs the restaurant for the ingredients while the price on the menu is the selling price. The ratio of these two prices is called the cost rate. In the case of a sushi restaurant, the ideal cost rate is 35% or less. A restaurant operating with only Omakase will have a cost rate of 40% with a focus on the quality of the toppings.
For example, every Frenchman knows that 
Famous for its Belon brand name, the oyster native to Europe has a flat, rounded shell. It belongs to the genus Ostrea. To be honest, Belon oysters aren’t sweet and don’t have a distinguished flavor compared to Japanese oysters, and the salty fragrance of the sea is dulled, so it can seem less flavorful.
Among the many sushi toppings, Pacific bluefin tuna, and actually the Madai (Red sea bream) as well, are toppings that are difficult for an amateur to tell whether it is farmed or wild. However, there is no need to worry about that when it comes to Tako (Octopus). There are no octopus farms to be found in the world, so it is a 100% wild topping.
Amateurs can’t tell the difference between domestic Tako or African imports. However, there is one aspect that even an amateur can use to distinguish between the two. There is one condition for this to work, and that is that at least one of the suckers is in-tact. The suckers are scraped off for most toppings, but in cases where they are sliced by the restaurant, there are often suckers remaining. If the sucker is pure white, it is almost definitely from Africa. Meanwhile, domestic Tako suckers maintain a faint red color in the suckers, even when boiled. The reason the suckers turn white seems to be an effect of the food preservatives added during processing, but this has not been confirmed.
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Hirame is a high-quality fish that goes for at least US $50 per kilogram. It can even exceed US $80 per kilogram, depending on the timing and the fish’s body.
Ishigakigai is a shellfish found from Kashimanada northward, Hokkaido, from the Kuril Islands to the Aleutian Islands and even on the west coast of North America. It lives off of plankton in the shallow sandy mud bottoms of the sea at depths of about 50 meters.
It starts to become common at the market when the Japanese rainy season ends, at the beginning of summer every year, which is around the end of the Torigai season. It then disappears from the market at the end of summer. A number of sushi restaurants start using it as a substitute for Torigai all at the same time, so Ishigakigai nigiri sushi suddenly started appearing on menus. Frankly, it is somewhat conservative as a nigiri topping but is known for the crunchy texture when biting into it. It also has strong sweetness and umami, which goes exquisitely with Shari. The sushi chef slaps the meat in his hand directly before serving to stiffen it–a way to increase the crunchy texture characteristic of shellfish. Naturally this texture is evidence of its freshness.
One type of shrimp that is used for nigiri sushi when still raw is Botan ebi. Needless to say, it is an extremely new addition to the Edomae sushi topping list. Interestingly, there are two types of domestic shrimp that are called Botan ebi in the Toyosu Market.
One is called by its Japanese name, Toyama ebi, with a length of 25 cm, lives in the sea at depths of 100 to 400 m, and is normally caught in Funka Bay of Hokkaido on the Japan Sea side. It actually isn’t caught in Toyama very often despite being called Toyama ebi. At the cheapest it still costs US $20 per kilogram, and in rare cases can exceed $200 per kilogram. In the Toyosu Market, it is called “Torabotan” because of the tiger stripes on the shell (“Tora” is Japanese for tiger).
In Japanese, when a compound word is made out of two individual words, and the first consonant of the second word changes from a “clear sound” to a “fuzzy sound”, it is called “Rendaku”. For example, Edomae (江戸前) + sushi (寿司) changes to Edomaezushi (江戸前寿司). However, the correct pronunciation is only generalized among Japanese people, so in this book we chose the most commonly searched version of each compound word.
Out of the five types of Amadai that live in Japan, Aka-amadai, Shiro-amadai and Ki-amadai are the three types offered in the markets.
The main characteristics of Aka-amadai are its overall red body, the bright yellow color under the eyes and how part of its fin is a shiny cobalt blue color. Aka-amadai is called “
Shirakawa is considered to be the finest of the Amadai and can cost more than US $100 per kilogram. Aka-amadai costs around US $40 per kilogram. Shirakawa always ranks in the top three fish for market price. Shirakawa has more elasticity than the other two and has rich fat, making it perfect as sashimi or a sushi topping. The umami is so strong that even when served raw, the customer sometimes thinks it’s been prepared using kobujime. The fat between the meat and the skin is sweet and the skin is delicious in its own right, so it can even be eaten as sashimi with the skin left on. The famous production sites include Tsushima in Nagasaki Prefecture and Yawatahama in Ehime Prefecture. They are in season from autumn to winter. However, they say in a catch of 1,000 Amadai, you can only get one Shirakawa, so it is a rare item you won’t often see, even in a high-end sushi restaurant.
Unagi distributed domestically in Japan used to include European eel, but currently, it is mostly Japanese eel. In Japan, the overwhelmingly most popular way to eat unagi is “kabayaki”. Kabayaki mainly refers to a grilled fish cuisine in which unagi or anago (conger eel) is prepared by slicing open along the spine and removing the bones and guts, then skewering it, and grilling without any seasoning, steaming it (Some area, unagi is just grilled longer without steaming. This results in the unagi a little crispier and chewier) after that, and finally dipping it in a sauce made from a mixture of soy sauce, mirin, sugar, sake, etc.
Oboro and Denbu look the same, and the ingredients are also pretty much the same. In other words, there are no clear differences between them, but what it is called differs depending on the restaurant’s policy and the locality. There are various theories for this, but there is no clear line distinguishing oboro and denbu.
Denbu (田麩) is mainly boiled white fish that is then loosened and made into fibers, then seasoned with sugar, mirin, salt, etc., then roasted until the moisture is gone. Some are colored with red food coloring (called sakura denbu) while others are left as the brown color similar to tsukudani. The appearance is as if only the fibers of the original ingredients remain. This is why it was written with the kanji “田夫” (the literal meaning of kanji: rice patty+husband). The word “田夫” means “someone from the countryside” or “rough-cut” and refers to the way the fish is turned into a coarse form by pulling the meat apart. It is also used as a coloring for chirashizushi, futomaki (large sushi rolls), bento boxes, etc.
On the other hand, Oboro (朧) is made by using a grinding bowl to break down the meat of shiba shrimp or white fish, then seasoning with sugar, mirin and salt before removing the moisture over low heat. Oboro is used for bara-chirashi, futomaki (large sushi rolls), etc., and is also sometimes used between the topping and shari (vinegared rice) in nigiri sushi. This gentle sweetness and the shrimp aroma are essential for Edo-style sushi. Making oboro is laborious work, so there are fewer and fewer Edo-style sushi restaurants that make their own oboro.