Combine the first 9 ingredients in a medium bowl. Add the roast and turn to coat. Cover, refrigerate and marinate overnight, turning occasionally. Take the meat out of the marinade, set on a plate and pat dry. Discard the marinade.
Preheat your barbecue to medium-high. Lightly oil the grill. Season the roast with salt. Set the beef on one side of the barbecue and sear on all sides. Close the lid and turn the heat off underneath the roast; leave the other side of the barbecue set to medium-high. Cook the beef until rare to medium rare, about 35 to 40 minutes, or until the centre of the meat registers 125 degrees F to 130 degrees F on an instant-read meat thermometer. If desired, brush the roast with barbecue sauce and heat through a few minutes. Set the roast on a plate, tent with foil and rest 10 minutes before thinly slicing.