Rinse the lemon, then peel it. (This recipe uses only the peel, so save the lemon for a different use.) Combine the water and sugar in a small saucepan. Cook over medium-high heat, stirring, until the mixture comes to a boil and the sugar has dissolved. Add the lemon peel, lower the heat, and simmer for 5 minutes. Let cool to room temperature. Strain the syrup through a fine-mesh sieve, then refrigerate until chilled.
Add the yogurt and honey to the chilled syrup and stir until thoroughly combined. Put a bit of the yogurt mixture into each of the molds, to a height of about 3/4 inch. Freeze until the mixture begins to set, about 40 minutes.
If the blackberries are big, cut them in half. Divide the blackberries among the molds, then pour in the remaining yogurt mixture, dividing it evenly among the molds.
If using conventional molds, snap on the lid and freeze until solid, 3 to 4 hours. If using glasses or other unconventional molds, freeze until the pops are beginning to set (45 minutes to 1 hour), then insert the sticks and freeze until solid, 3 to 4 hours. If using an instant ice pop maker, gently fold the blackberries into the yogurt prior to filling the molds and follow the manufacturer's instructions.
Reprinted with permission from Paletas: Authentic Recipes for Mexican Ice Pops, Shaved Ice, & Aguas Frescas by Fany Gerson, copyright (c) 2011. Published by Ten Speed Press, a division of Random House, Inc.