Poke the steak with the tines of a fork to allow the marinade to penetrate the meat.
In a bowl, combine soy sauce, Worcestershire sauce, olive oil, garlic, vinegar, brown sugar, and black pepper.
Place the steak in a large resealable bag and pour the marinade over the steak, ensuring it's well coated.
Seal the bag, place it in the refrigerator, and let the steak marinate for at least 4 hours or overnight for better flavor.
Preheat your grill to high heat, and remove the steak from the marinade.
Grill the steak about 4-5 minutes per side, depending on thickness, for medium-rare doneness.