01 - Place watermelon cubes and strawberries in a blender container.
02 - Pour in lime juice and sweetener if using.
03 - Blend until completely smooth. Taste and adjust sweetness as needed.
04 - Pour mixture evenly into popsicle molds, leaving space at top for expansion.
05 - Place popsicle sticks into center of each mold.
06 - Freeze for at least 4 hours or until completely solid.
07 - Briefly run mold under warm water to release, then gently pull out popsicles.