Pappasito's Fajita Marinade - for Flank Steak or Chicken

The secret to Pappasito's Fajitas is their marinade and their tenderizing process: they repeatedly pierce the flank steak with a tenderizer fork; put it in a thick, tough, vacuum bag; add the marinade; remove all air after adding the marinade; and then seal the bag. And then, and here's the difficult part, they throw the bag into a rotating tumbler drum (kind of looks like a small cement mixer with internal baffles) which beats the hell out of the meat over night). You need to marinate for at least 8 hours. For cooking, they get the grill as hot as possible and sear on each side for only about 1.5 to 2 minutes (for the flank steak -- always cook your chicken well). The good news is that I do everything they do except the cement-mixer step and the end result is still very good. I typically marinate for a fairly long time to compensate.