Katsuo no Tataki (lightly-roasted bonito) (鰹のタタキ)

Katsuo no tataki is one of the fish dishes made with katsuo (bonito or skipjack tuna). It is also a type of sashimi (slices of fresh raw seafood). It is a dish made by first cutting katsuo into fushi (ship-shaped form), and after roasting the surface only, it is cooled down and cut into pieces followed by the addition of condiments and sauce (made with soy sauce, sake, and other seasonings).
It is also called 'Tosazukuri.'

Its origin is said to have been a staff meal for fishermen. There is also a theory on how katsuobushi (dried bonito) was derived, that states that while katsuobushi was being made, the rest of the fish got stuck onto the skewers and became roasted with the skin on. There is another theory on the origin that states that Katsutoyo YAMAUCHI, the lord of the Tosa Domain, forbade eating of perishable raw katsuo in order to prevent food intoxication, and instead, it was eaten only after roasting the surface disguising it as grilled fish.

Tataki in general

So-called Katsuo no tataki. Fresh katsuo that has been de-scaled, is cooked with its skin. Katsuo is cut into five fillets, their skins are seared so that only the surface is slightly cooked, and they are then left to cool.
Seasonally and also for its aroma, rice straw is usually used as fuel (Warayaki katsuo, bonito roasted over the straw-fueled fire, which is popular for its savory early-summery aroma, is cooled down naturally in order to keep its aroma.)
After being dried with paper, they are sliced into about 1 cm pieces with a sashimi knife, stacked on a big plate and served with sufficient amount of condiments and sauce on top.

They are patted with fingers to blend and stood in the refrigerator for about an hour.
(Refer to tataki)

As for the origin of the name 'tataki,' there are various theories, however, it remains unclear.
It ranges from actual 'tataki' (patting) with condiments on meat, 'tataki' (beating) with a wooden stick after roasted and sauced, to 'tataki' without any physical act of 'patting' or 'beating.'

It is eaten by seasoning raw katsuo fillet with extra coarse salt and roasting it over the straw fire, slicing it into sashimi while it's hot, and serving it with condiments and sauce, or by patting the sashimi with the flat part of a knife on a cutting board to blend the added condiments and sauce.

Condiments: chopped flavored vegetables in seasonings like green onion, garlic, shiso (Japanese basil), fresh Japanese pepper leaves, Japanese ginger, fresh onion, oroshi shoga (grated ginger), sliced green chili and so on.

Sauce: sanbaizu (vinegar, soy sauce and mirin (or sugar) mixed in roughly equal proportions), tosazu (vinegar flavored with dried bonito shavings, konbu kelp, sugar and soy sauce), soy sauce with citrus fruits or yuzu (Japanese citron), soy sauce with ginger and so on, and the combinations differ according to the eastern part or the central part of the prefecture. Some people eat it only with yuzu juice and without any sauce or vinegar.

Relishes: Japanese ginger, udo, cucumber, ryukyu and so on.

Chiai (meat of a fish that is dark red with blood, usually coming from the parts close to the spine) no tataki

It is a kind of dish eaten mostly in the production area of katsuobushi. The name came from the brisk rhythm of a knife tapping on cutting board while cutting katsuo into pieces.

The dark red parts of the meat called Chiai located in between the back and abdominal areas of fishes are gathered, and chopped into pieces. While so doing, condiments like green onions are added, and they are chopped with a knife by tapping to blend the ingredients. An experienced person can use two knives rhythmically.

Vinegar is added to give it an acidic taste making it edible.