http://www.simplyrecipes.com/recipes/grilled_skirt_steak_skewers/
If using bamboo or wooden skewers, place them in a dish, cover with water to soak.
Place all marinade ingredients in a small bowl, stir to combine. Set aside.
Lay the skirt steak horizontally out on a cutting board. Notice the grain of the steak that goes up and down.
Cut the steak into segments (along the grain of the meat), about 6 to 8-inches long.
Then, with each segment, turn the segment so the grain of the meat runs in a line from left to right, and cut thin strips (1/4 to 1/3-inch thick, 1 1/2-inch wide, 6 to 8-inches long), angling the knife, cutting across the grain.
Place the steak slices in a non-reactive bowl or casserole dish. Toss with the marinade to coat. Chill and marinate for at least 30 minutes, up to 2 hours.
Preheat your grill, whether charcoal or gas, for high-direct heat. While the grill is preheating, thread the marinated skirt steak strips onto your pre-soaked skewers.
When ready to grill, brush the grill grates with olive oil (helps to fold a paper towel, soak the towel in olive oil, and use long handled tongs to hold the soaked paper towel and spread oil on the grates).
You know your grill is hot enough when you can only stand to hold your hand 1 inch above the grill grates for one second.
Working in batches if necessary, lay the skirt steak skewers on the hot grill grates, perpendicular to the grates. Grill for 3 to 4 minutes per side, until cooked through.
Remove from grill and let sit for a few minutes before serving.