I first realised there might have been a photo here last week when I was experimenting but haven't managed to get a result I've liked until now.

I like this :)  Especially the vapourised metal shooting off the oven ring after the spark has struck!

Used my macro lens and the full range of extension tubes to get as close as I possibly could to the action then focused manually to get as much of the spark (and secondary sparks) in focus as possible - at f2.8 my DOF was NOT large!

Strobist - YN560II through diffuser lighting the sparkplug and oven hob ring, 1/128th power about 5cm away.