Mix all the ingredients together, except the meat, to make a marinade. Pour over the skirt steak, in a non-reactive container (not metal), cover, and stir occasionally for six to eight hours.
Fajitas can be cooked in several ways. If you have the space, smoke the fajitas for 30 minutes with pure mesquite smoke, and then cook for 4-7 minutes per side over direct heat--mesquite coals being the heat of choice. Baste with the marinade throughout the cooking process. If you need to cook completely over direct heat, then use a fairly slow fire, about like you should use when grilling chicken, and cook, covered if possible, for about 10 - 15 minutes per side, basting with the marinade.
4 jalapeno peppers -- pierced
3 tablespoons chili powder
1 teaspoon cayenne pepper
1 8 oz bottle herb and garlic oil-based -- salad dressing
1 can beer
1 1/2 teaspoons garlic powder
4 small Mexican limes -- juiced
2 teaspoons cumin powder
1 large onion -- minced
2 tablespoons cilantro -- minced
1 tablespoon Worcestershire sauce
1 bay leaf
3 pounds skirt steak