Preheat your grill to high heat (450°F+), set up with a rotisserie. Trim any excess fat or silver skin from the surface of the roast. Combine all rub ingredients and mix well.
Apply a thin layer of oil to all surfaces to help bind the rub to the meat. Apply a generous amount rub to all surfaces. Thread the roast onto the rotisserie spit rod and secure in place. Properly position the spit rod in the grill. Cook until the internal temperature reaches 130°F. Remove the roast from the spit rod and allow to rest 10-15 minutes before slicing thin slices across the grain.
To make the chimichurri, place all the ingredients into the food processor. Pulse until all ingredients are chopped and well combined. Adjust consistency with more olive oil for a looser sauce. Taste and adjust seasoning, as needed. Serve the chimichurri alongside the sliced tri-tip.