Place all ingredients in a zip bag, and zip shut. Smush it around good so the marinade is on all of the steak. Place in refrigerator 3-4 hours, or overnight. Remove from refrigerator 1 hour before cooking.
Cooking the Beef
Preheat grill, or grill pan, to high heat (aim for 450-500*). Remove flank steak from bag, wiping off any pieces of garlic (they'll burn quickly, not tasty!). Place steak on hot grill and cook approximately 7 minutes on 1 side; flip. Cook on second side until desired doneness. Remove from grill and let rest 5 minutes before cutting. Thinly slice AGAINST the grain. Serve with Bleu Cheese Sauce.
Notes
I cook my steak to medium rare to medium. That's an approximate total time of 8 minutes for medium rare, 10 minutes for medium. The key is to slice against the grain or your meat will be tough to chew. When you look at flank steak, you'll see the grain runs the direction of the longer edge of the steak. Use a very sharp knife, or a serrated knife works great. I angle my knife on the diagonal so that it slices to a broader piece.