1 BJJ technique? I don't know what you mean by technique, because something like armbar is pretty broad. Is it applied from a certain position? What's the deal?
Anyway, if it's just one technique in any style, I'm going to go with that flying heel hook a-la Ryo Chonan v Anderson Silva. No one ever sees it coming.
Sig by Toxic
Barnett - Toquinho -Werdum - "Nurmie"
Z. Gurgel - Morango - Rocha - Tiequan