Skirt steaks cook in a flash—less than 8 or 10 minutes—but should be marinated first in a brew bolstered by a flavorful acidic ingredient such as the pomegranate juice used here, fortified by the molasses. Although skirt steaks are relatively inexpensive, it's a good idea to buy USDA Prime or Wagyu steaks and pay close attention when you grill them. This way you will be guaranteed tender, absolutely delicious meat.
With a mortar and pestle, roughly crush the black and green peppercorns and the salt.
In a small bowl, stir together the pomegranate juice, molasses, oil, shallots, and the chili paste. Stir in the crushed pepper mixture; you should have about 1 1/4 cups of marinade.
Lay the steaks in a single layer in a shallow glass or ceramic dish. Pour the marinade over the meat. Turn the meat to coat; cover, and refrigerate for at least 2 hours, letting the meat come to room temperature before grilling.
Prepare a charcoal or gas grill: Lightly spray the grill rack with vegetable oil cooking spray. Light the coals or heating elements, and let them burn or heat until moderately hot to hot.
Lift the steaks from the dish, letting most of the marinade drip off. Pat the meat dry and set it aside at room temperature for about 15 minutes.
Grill the steaks for 2 to 4 minutes on each side for medium-rare, depending on thickness, or until they are cooked to the desired degree of doneness. Let the steaks rest for about 5 minutes before slicing and serving.