This recipe comes from, "The Black Dog" restaurant on Martha's Vineyard. It's my favorite beef fajita recipe, by far! Grilling the beef really makes a difference in flavor and the blend of spices are perfect. However, if you don't want to grill, the beef can be done using a cast iron pan on the stovetop. The beef will have a more intense flavor if you let it sit in the refrigerator for a few hours after applying the dry rub. You can also make the salsa, slice the onions and peppers ahead of time. Whether you're entertaining or just have a hankering for a really good beef fajita, this recipe rocks.