
Preheat your grill. Set up your grill for high-heat direct cooking at 400-450 degrees F.
Char the jalapeño. Drizzle the jalapeño with a little olive oil. Place on the grill grates and cook for 3-4 minutes per side until blackened all the way around. Transfer to a plate and allow to cool slightly. Remove the stem. You can also remove the seeds and ribs for less spice.
Combine ingredients. In a food processor, combine all of the ingredients for the chimichurri, including the roasted jalapeño.
Blend. Pulse until well combined, but you can still see small pieces of the herbs.
Enjoy. Pour the chimichurri sauce into a serving bowl, cover, and store at room temperature until ready to use. This sauce can be made several hours in advance. Leftovers can be stored in the refrigerator for up to 3 days. You will want to remove the sauce from the fridge at least an hour before using it to melt the olive oil if it has solidified. Stir the chimichurri before serving as the sauce has a tendency to separate.