Take steak out of the fridge and let come to room temperature for about 10 minutes.
Meanwhile combine olive oil, Worcestershire sauce, chilli sauce and brown sugar in a bowl. Mix well. Add steak to the marinade, turn to coat and marinate for 10 minutes at room temperature.
Lightly oil the grill grate and place it just above the charcoal. Place steak on the grill and sear for about 1 to 2 minutes on each side. To flip the meat use tongues or two wooden spoons. Don't prick the steak with a grill fork.
Move the grate further away from the heat and grill the meat 3 more minutes on each side, or until done to taste.
Take off the grill, cover with aluminium foil and let rest for 10 minutes. Sprinkle with salt and pepper to taste and enjoy.