Preheat charcoal grill with coals placed on one side of grill.
Mix cilantro, garlic, lime zest and extra-virgin olive oil in a large bowl and rub all over steaks.
Place hickory wood chips directly on coals and place steaks on grill surface over coal area.
Cover grill and grill flank steaks for 5 minutes. Turn steaks 90°, cover grill and grill for 5 more minutes.
Flip steaks, cover grill and grill 5 more minutes. Move steaks to cool part of grill, cover and continue cooking until internal temperature on instant-read thermometer registers 120°F.
Let rest at least 10 minutes and slice thinly against the grain. Enjoy!