Combine all the marinade ingredients in a medium bowl, whisking to combine.
Place flank steak in a large glass bowl (or zip top plastic bag), and pour marinade over. Toss to coat the meat completely.
Allos to marinade for 2 hours and up to overnight.
When ready to grill, preheat grill to 500º. Place flank steak on the grill for 4 minutes, and then flip to other side. Cook until desired internal temperature is reached. If you're looking for medium to medium-rare, this should take about 5 minutes, and the temperature should read 130º.
Remove steak from grill and tent loosely with tin foil.