Brew the black tea and let it cool completely to room temperature or chill in the refrigerator for faster cooling.
Pour the cooled tea into a blender, then add the fruit juice for a hint of sweetness and flavor.
Sprinkle in the ice cubes and secure the lid on the blender.
Blend the mixture on high speed until the ice is finely crushed and the mixture has a slushy, granular texture.
Taste the slushie and add more fruit juice if a sweeter flavor is desired; briefly pulse to incorporate.
Pour the frozen, granulated slushie into glasses, using a spoon or spatula to serve if needed.
Enjoy immediately with a straw and a fun follow-up photo to showcase the crunchy, icy texture.