Hibiscus is a flower with petals that are dried into a tart infusion for teas and aguas frescas. According to Salas, "Hibiscus is a perfect addition to margaritas because it brings a tart, cranberry-like flavor that complements lime and tequila due to its subtle floral sweetness." Furthermore, it imparts a deep red hue to any liquid infusion, which Salas says "[makes] for a visually striking cocktail that's perfect for snapping photos or impressing guests."
I won't pretend that these are the height of Italian fashion, but style is eternal as is the childish joy of a bright yellow frozen lemon. You could, of course, buy in lemon sorbet instead, and use the flesh from the lemon shells for cocktails or lemonade (and/or freeze the juice for future use), but this really is such an easy make-ahead dessert that I urge you to give it a go.