Mix the first 7 ingredients together.  Rub the spices on the flank steak.  Let those spices and flank steak hang out together for 1 hour or up to overnight. 

Heat a grill, or a grill pan, over medium-high heat.  Cook 8-10 minutes, turning every so often, for medium-rare.  Reduce cook time for rare, increase for medium to well.  Remove from the heat and let rest for about 10 minutes. 

Toss your corn tortillas on the grill, char them up just a tad. 

After the flank has rested, slice against the grain.  Key, against the grain guys.  Throw in the tortillas with fixings of choice.