Place flank steak in shallow baking dish. Combine 1/4 cup wine and 1 Tbsp. garlic in small bowl. Pour over steak and refrigerate 2 hours. Turn steak, and marinate another 2 hours.
Mix salt and pepper in small bowl.
Combine olive oil, 2 Tbsp. wine, remaining garlic, parsley, oregano, chili flakes, and ½ teaspoon of the salt & pepper mixture in a blender or food processor. Blend, then transfer to a small bowl and refrigerate.
Heat grill to high. Remove steak from marinade and season both sides with salt & pepper mixture. Grill about 4-5 minutes per side depending on thickness of steak, turning once. (The internal temperature in the thickest section of steak is 125°F for medium rare.) Remove steak from grill, cover and let rest 8-10 minutes.