In a small saucepan, heat half of the cranberry juice and lime juice with the agar agar, until it’s simmering. Stir for a few minutes, until the agar agar is fully dissolved.
Quickly add the rest of the juices, stir, then add your booze.
Pour the mixture into a square pan and chill for a few hours, until everything is gelatinized.
Flip your jello shots onto a flat surface, like a cutting board, and slice them into cubes. Grate some lime zest over them, and you’re ready to serve!