Thanks, Renegade, for this bad ass post on the SRK SFIV Zangief forum.
Turns out the Red Cyclone has a kara!
Kara effectively meaning "empty" in Japanese. I was first introduced to kara cancels in Third Strike, wherein the animation of a command attack (say Akuma's f+mp) can be quickly cancelled into his throw, increasing the throw's range. Why, it's even possible at extreme levels of technical proficiency to execute a "kara demon", or a kara cancel into the Shun Goku Satsu.
Anyways, apparently there are a few handy kara throws in SFIV (Ken, I've learned) but this Renegade fellow has enlightened me to the fact that Zangief's standing Roundhouse, which I previously praised for it's ability to move forward under Zanku Hadokens, can be cancelled within the first two frames into EX Banishing Flat to punish blocked Rolling Attacks (both horizontal and Backstep) from an opposing Blanka.
To simplify (?):
Blanka Rolling Attack blocked;
Zangief (reversal) s.Roundhouse xx EX Banishing Flat
So glad to hear, as the Blanka matchup is a real pain for Zangief. Electricity shuts down a lot of options in this pairing, so any way to inflict damage is a boost.
Can't wait to give it a shot.