01 - Place the watermelon cubes and strawberries in a blender container.
02 - Pour in the lime juice and sweetener if using.
03 - Blend until completely smooth. Taste and adjust sweetness as desired.
04 - Pour the mixture evenly into popsicle molds.
05 - Insert sticks and freeze for at least 4 hours, or until solid.
06 - To remove, briefly run the mold under warm water and gently pull out the popsicles. Serve immediately.