Add the guava jelly and garlic in a small saucepan over medium heat and cook until the jelly has dissolved. If the jelly is not dissolving, add a small amount of water just to help it along.
Remove it from the heat and add the tequila and lime juice.
Season the fajitas with salt and pepper and brush them with the glaze.
Heat your grill or cast-iron skillet to medium high heat.
Brush the grill with oil and lay your skirt steak on the grill or skillet.
Allow the meat to caramelize. Cook for five minutes on each side while basting with the glaze.
