Try doing 1.5 ounces of reposado tequila, 1/2 ounce of a good quality grenadine and cream de cassis or if you don't have cassis use creme de mure, 3/4 of an ounce of lime juice and a drop of angostura bitters and shake it all together and then top with club soda and a pinch of salt or Topo Chico. This variation comes from Anders Erikson and I found it to be delightful.