Score the flank steak by making shallow crisscross cuts on both sides.
Place the olive oil, light brown sugar, red wine, soy sauce, onion powder, honey, green onions, garlic cloves, garlic vinegar, ground ginger, and garlic powder in a blender. Puree until smooth; pour mixture into a resealable plastic bag. Add the steak, coat with the marinade, squeeze out excess air, and seal the bag. Marinate in the refrigerator overnight.
Preheat an outdoor grill for medium-high heat, and lightly oil the grate.
Allow the flank steak to rest at room temperature for 20 minutes. Remove the steak from the marinade, and shake off excess. Pour the marinade into a small saucepan and bring to a boil over high heat. Reduce heat to medium-low, and simmer for 10 minutes; set aside.
Grill the steak on the preheated grill until it starts to firm, and is reddish-pink and juicy in the center, about 7 minutes per side, basting often with the sterilized marinade. An instant-read thermometer inserted into the center should read 130 degrees F (54 degrees C).
