Bring 1 cup water to a gentle simmer in a small saucepan. Remove from heat, add 2 tablespoons dried hibiscus petals, cover, and steep 10 minutes. Strain through a fine mesh sieve into a heatproof bowl, pressing gently on petals to extract color and flavor. Discard petals and let liquid cool to room temperature.

Combine grapefruit and agave

Measure 1 cup fresh pink grapefruit juice (about 2 medium grapefruits). In a mixing bowl or jar, whisk together the cooled hibiscus concentrate, grapefruit juice, and 3 tablespoons agave nectar until the agave is fully dissolved.

Add salt

Stir in 1 teaspoon coarse sea salt gradually, tasting as you go. The salted agave element should add a gentle savory lift without making the drink overtly salty. Adjust up to 1 1/4 teaspoons if you prefer a more pronounced saline note.

Herbal & Sparkle

Infuse rosemary

Lightly bruise 1 rosemary sprig by rolling it between your palms or gently tapping with the back of a knife to release oils. Add bruised sprig to the grapefruit–hibiscus mixture and let steep 5 minutes at room temperature for a subtle herbal note. Remove and discard (or reserve for garnish) once desired aroma is reached. If you prefer stronger rosemary, steep up to 15 minutes.

Assemble the mocktail

Fill two serving glasses with ice (about 1 cup ice per glass). Divide the grapefruit–hibiscus base evenly between the glasses (about 3/4 cup base per glass). Top each glass with chilled sparkling water (about 1 1/2 cups total divided; roughly 3/4 cup per glass). Stir gently once to combine, taking care not to flatten the bubbles.

Garnish and finish

Garnish each glass with a thin slice of pink grapefruit and a fresh rosemary sprig. Optionally float an edible hibiscus petal for color. Serve immediately while sparkling.