In a large glass baking dish, whisk together the Carne Asada marinade ingredients (jalapeño through black pepper) until combined.
Add the skirt steak in a single layer, turning to coat with the marinade. Cover and refrigerate for at least 1 hour, but no longer than 8 hours (longer will begin to break down the meat – see recipe note #3).
When ready to grill, preheat an outdoor grill to medium-high heat.
Grill steaks for 7 to 10 minutes per side, turning once for medium-rare.
Remove steaks from the grill and allow them to rest for 5 minutes.
Slice thinly across the grain and serve.