Make the marinade by mixing together the oil, soy sauce, Worcestershire sauce, lime juice, garlic, chili flakes, salt and pepper together. Place the flank steak in a shallow dish and pour the marinade all over the meat. Flip the steak so that it is evenly coated. Cover the dish with plastic wrap and place in the fridge to marinate for a minumum of 2 hours.
Heat the grill over high heat so that the temperture is around 500F.
Slowly lay the flank steak on grill and cook with the lid open.
Let the steak cook for about 3 minutes. Turn the steak 45 degrees and cook for 3 more minutes.
Flip the flank steak and cook for 3 minutes. Turn it 45 degrees again and grill for 3 more minutes, or until it reaches your preferred doneness (125F for rare - 130F for medium rare - 135F for medium).
Take the flank steak off the grill and let rest for 5 minutes before slicing. Carve the steak into thin slices against the grain.