Fajitas are part of Tex-Mex cuisine that originated with vaqueros. These cattlemen were sometimes paid with undesirable portions of meat called skirt. They would grill them directly over an open flame and serve them with fresh tortillas to make steak fajitas.  Today, fajitas are thin strips of meat grilled with vegetables and served with tortillas and toppings like sour cream and Pico de Gallo.