make the mojito layer
In a blender, puree all of the ingredients except the xanthan gum on high speed until smooth and bright green, about 30 seconds. Pour into a bowl. Slowly sprinkle the xanthan gum over while quickly whisking, until slightly thickened and foamy. Let rest for 15 minutes, then skim any foam. Pour 1 1/2 tablespoons of the mojito layer into eight 3-ounce popsicle molds or paper cups. Freeze until almost firm, 1 hour. Poke a popsicle stick into the center of each.