My favorite way is to grill over mesquite flame leaving the meat extremely rare (it'll cook more on the sizzle platter). It gets a great smoke flavor to it that way. To me, being as it's technically steak, it needs to be rare, and a slow smoke would tend to leave it dry and tough. That is, of course you'e wanting to smoke it and shred it.
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I usually buy flank steak and use Claude's Fajita Marinade (I like to add a little lime juice), but $1.99/lb is a steal.
Tim