Ice size is non-negotiable: use one large cube (silicone sphere molds work great) or 2-3 standard cubes. Don't skip fresh lime — bottled lime juice makes the drink taste flat. The mint is not just decoration; it primes your palate with freshness before you sip. To batch for a party, mix the base (guava, pomegranate, lime) in a pitcher and refrigerate up to 3 days. At serving time, fill glasses with ice, pour base halfway up, and top each with sparkling water. Garnish per glass. For a kid-friendly version, use ginger ale instead of sparkling water. To turn it into a cocktail, add 1.5 oz white rum or vodka to the base and reduce guava nectar by 1 oz.