Place meat in a baking dish large enough to fit the skirt steak (or use sealable food-storage bag). Add the lime zest and lime juice, green onions, garlic, cilantro, olive oil, coriander, cumin, chili powder, salt and pepper. Turn several times to coat the meat. If you are using a baking dish cover before placing in refrigerator. Marinate in the refrigerator for 12 to 24 hours turning every so often to coat both sides of meat.

When outdoor grilling set grill 6 to 8 inches above charcoals or gas jets and heat grill surface. When grill and charcoals are ready you should be able to hold your palm over the grill for about 2 seconds and there should be a light ash coating on the glowing coals.

Remove the skirt steak from the marinade. Place meat presentation side down on the hot grill. Grill the steak 2 to 3 minutes per side for a medium rare steak.

Transfer steak to a cutting board, tent with aluminum foil and let rest for 5 minutes.
For maximum tenderness, slice the steak very thin at a slight angle against the grain.

Note: The skirt steak, now often referred to as fajita steak, is similar to flank steak (which can substitute). The acidic marinade helps tenderize and season it. Best cooked no further than medium-rare.