Tataki is tuna cut from the loin, seared or flamed on all sides.
Visually, tataki is an eye-catcher simply because of its dark red color - tataki is cut into slices.
The combination of fresh, raw fish and roasted aromas is often served with hot pastes (e.g. wasabi) or umami-heavy sauces with a subtle acidity (e.g. ponzu . . .