Place all the ingredients except the skirt steak in a gallon sized ziptop bag and mix well. Now place the skirt steak in the bag and let out almost all the air. Seal the bag and massage the marinade to cover all the meat well. Place the bag in your refrigerator overnight for best flavor. *
When you're ready to cook:
Take the steak out of the fridge at least 15 minutes before cooking to bring the meat to room temperature.
Heat your grill to medium-high, about 400°F. Be sure to oil the grates to prevent sticking.
Take the steaks out of the bag and place them on the grill.
Cook for 4 minutes on each side. Let the steaks rest for 5 minutes before slicing.
Add all the ingredients in a mixing bowl and mix thoroughly. Set aside to let the flavors blend.
* If you want to make the steak the same day, you can marinate the steak using the same method, but leave the bag on the counter for 2 hours. Yes, it's safe. However, I do not recommend anything less than the 2 hours.
Meat can stay remain unrefrigerated for up to 2 hours. By leaving it out on the counter, it stays at room temp which makes for more even cooking.
** Chimichurri Sauce - Make the chimichurri sauce and refrigerate an hour ahead of time for the best flavor!