Add all of the ingredients except for the shallot and optional chopped Fresno chili to a blender or food processor.
Pulse until the ingredients are well chopped, but not completely puréed. Use a spatula to scrape down the sides to process evenly. Transfer the chimichurri to a container and add the shallot or onion and the Fresno chili.
Taste for seasoning and add more salt, red wine vinegar and pepper flakes as desired for your taste.
Cover with plastic wrap directly on top of the chimichurri and store in the refrigerator until you are ready to use it.