Wipe the beef and put in a large food bag. Mix together all the remaining ingredients, then pour into the bag. Massage marinade into the beef, then put on a plate in the fridge for at least 2 hrs, or overnight if you have time.
Light the barbecue, allowing time for the coals to turn grey. Season the beef with salt and pepper, then cook for 8-10 mins on each side until well browned. Spoon over a little of the marinade as it cooks.
Remove the beef from the barbecue and set on a board. Cover tightly with foil and leave to rest for 10 mins. Cut the beef across the grain into slices.