Just in at Sushi Kuni (my pop's restaurant): RAW OCTOPUS (nama dako)! Kuni ordered this long, spindly tentacled arm last week straight from Tsukiji market. It was over three feet long, with a gorgeous purple-pink tone. I can't quite put my finger on why, but there's something oddly sexy about it.
Kuni lightly blanches it, only for a moment, so that it's still raw in the middle. No vinegar necessary to tenderize it! Normal octopus is usually boiled thoroughly, often with vinegar, which is what makes this so especial.
Unlike usual octopus, which can get flavorless after so much chewing, this was so tender and sprightly! I would even say a bit crisp-- like good mirugai (geoduck). I loved the texture. Kuni just sprinkles a bit of salt on it, and with a squeeze of lemon, it's a pillowish, magnificent bite. I would recommend it sashimi style-- don't ruin it by adding rice to it.
For your nerds, here's a great article by master food scientist Harold McGee about preparing octopus.