Remove the roast from the marinade. Wipe off excess marinade. Season with Oakridge BBQ Santa Maria Seasoning. Smoke at 250°F until the internal temperature reaches 110°F. Remove from the grill. Cover loosely with foil.
If you have a two-piece diffuser, remove the door and place GrillGrates over the firebox. If you have a one piece, completely remove the diffuser plate. Turn the grill up to 475°F.
When the grill comes up to temp, grill the roast on both sides to achieve nice grill marks. Remove when the internal temperature reaches 125°F. Rest 10 minutes before slicing thin, against the grain.