Add flank steak to an air-tight plastic container and add in all the marinade ingredients.
Seal the container and give is a little shake.
Refrigerate for 3-6 hours.
Pre-heat the grill to medium. Give it about 10 minutes to warm up.
Remove the flank steak from the marinade and grill about 6 minutes per side. If the flank steak is thicker or you like it more well done, you can cook 8 minutes per side.
Let the flank steak rest for about 5 minutes before cutting it. Then serve immediately.