1. Mix together all ingredients, that aren't the skirt steak, in a bowl. Place the marinade and the skirt steak in a large ziplock bag and let it marinade in the fridge for at least 4 hours or up to 24 hours.
2. Take steak out of fridge while you heat up your BBQ. You will want to grill the steak over direct heat at about 400F.
3. Grill the skirt steak until it is nicely browned on both side and done to your liking. We like our flank steak done medium-rare, so you want to cook it until the thickest part has an internal temperature of 125 F. About 3 - 4 minutes per side.
4. Transfer the steak to a cutting board and let it rest for 10 minutes.
5. Slice the steak against the grain and serve. We had it with some rice! yum.