Sometimes it's just too hot for a slice of pie. Fany Gerson, the New York-based author of the newly released Paletas, has a frozen solution. Her cookbook is packed with recipes for Mexican ice pops, aguas frescas and shaved ice. In her lime-pie pop, she combines the best of tart lime pie-including the graham-cracker crust--and a heat-defying ice pop, creating a frozen-on-a-stick masterpiece. Like all the recipes in her book, these pops are inspired by the traditional Mexican ice pops, or paletas, of her youth. The technique is easy: whisk, pour, freeze, eat. But don't skimp on squeezing fresh lime juice; it's the pucker in the pudding.