電光石火
den.kou.se-.kka

Literally: electricity – light – stone – fire

Alternately: A very short span of time. Alternately, incredible speed of motion. “Lightning-flash and sparks (struck from a stone),” as examples of things that happen quickly.

Notes: The parts can also be given in reverse order, 石火電光 (sekka-denkou). Apparently some people write sekka as 石下 (stone – down), but this loses the meaning of sparks and is an error.

So all the top results of the image search were for this oddly hamburger-shaped okonomiyaki. I’m sure there’s a perfectly reasonable explanation somewhere.