You can find fresh homemade chicharrón at most Mexican markets. If you can choose between airy, thin pork rinds and thick, meaty pork rinds that are ever so slightly curled at the edges, opt for the former. The purpose of putting pork rinds in these cookies is to amp up the flavor with a smoky and salty oomph. Having said that, the commercial brands of chicharrón will also work just fine in this recipe. (Lesley Téllez prefers Baken-Ets brand, which you'll find at most grocery stores.)