Add all ingredients for the chimichurri sauce to a food processor and pulse until well-combined but still chunky. Transfer to a jar and set aside until ready to use.

Stir together the ground coffee, chili powder, onion powder, mustard powder, and sea salt in a small bowl.

Rub the whole surface of the tri-tip with the rub and gently pat into the meat. Place meat in a casserole dish and refrigerate 1 to 6 hours. When ready to grill, place tri-tip on a plate and allow meat to come to room temperature - this ensures the meat will grill evenly.

Preheat the grill to medium or medium-low (about 350 to 375 degrees F). Brush off the grill if there are any leftover food particles on it.

Once hot, place the meat on the grill and close the cover. Cook for 15 minutes on one side. Flip, and cook another 15 minutes. Meat should feel firm, yet juicy and springy. For rare tri-tip, cook to an internal temperature of 120 degrees F. For medium-rare, 130 degrees F, and for medium, 140 degrees F. Note: Tri-Tip takes roughly 12 to 15 minutes per pound to cook.

Transfer the tri-tip to a plate or a cutting board and allow it to rest for 10 to 15 minutes. This allows the juices in the meat to travel throughout the meat and seep out, making it tender, and helping to make cutting the meat easier. The meat will continue cooking while it's sitting, and the internal temperature will increase about 6 to 10 degrees.

Heat corn tortillas in the oven or over the stovetop until warm and toasted. Cut the tri-tip into slices or cubes and add desired amount of meat to each tortilla. Top with chimichurri sauce, pickled red onions, and cotija cheese.