This is sometime called "Tosa-zukuri".
Because it is regional dish of "Tosa".
"Tosa" means Kochi-prefecture.
Oridinally it is a fisherman's dish.
"Katsuo" means bonito. It is a typical early summer fish in Japan.
Filleted bonito is grilled lightly.
Just surface of filleted bonito was grilled.
But inside is still raw.
And put into water with ice.
And sliced thicker than sashimi.
Usually we pour Tare(sauce) on it.
and seavr some vegetables(sliced onion, Shiso leaf ,grated ginger , sliced garlic and so on ) on it.
Photo above is "Katsuo no tataki" which is before sliced.
It is on the fresh fish counter in the supermarket.