I main mid, and from my experience, strategic midlaners (particularly
who has true damage on her Q return), can work well. They can set up kills easily, have great mobility to dodge all the CC tanks usually bring to the table, and with void staff and maybe sorcs, you can do plenty of poke damage to even tanks (you have to remember to itemize right too, not just pick a good champ).
You should think of picking midlaners like Ahri, though I don't know who does as good of a job as Ahri at what she does. She has all those handy things to fight tanks in 1 package.
Also you can convince your ADC to pick Vayne, and or your jungler to pick Vi who both do % damage based off of health and can blow tanks up as long as they aren't bad at them (or kog'maw if your in high enough elo to where people can play kog well).