Mix everything together and smear it over the steak. Refrigerate for a day or overnight.
Before grilling, let the steak come to room temperature for an hour or two. Set the BBQ to its highest setting and let it heat to full temperature. Lay the steak over the flames to sear with the lid open. After 3 or 4 minutes, rotate it 45 degrees to create a crosshatch pattern and sear for another 3 or 4 minutes.
When you have a nice sear on one side, turn the steak over and sear the other side the same way. If your steak is a bit thicker, you can turn the heat down to medium-low and close the lid. Check it every couple of minutes until it reaches your preferred doneness.
Let the steak rest for 10 minutes to release its juices, then slice across the grain into 2.5 cm (1 inch) strips.