Preparation Bring 1 1/2 cups water to a boil in a small saucepan. Stir in hibiscus and basil sprig. Remove from heat, cover, and steep for 20 minutes. Strain through a fine-mesh sieve into a small bowl. Cover and chill hibiscus tea until cold, at least 1 hour. Meanwhile, blend quartered strawberries in a blender until finely puréed. Transfer to a large bowl; add tea, agave syrup, and 1 tablespoon lime juice. Season to taste, adding more agave and lime juice, if desired. Pour strawberry mixture into a 13x9x2" metal pan and freeze until top layer begins to harden, about 2 hours. Using a fork, scrape mixture to break frozen portions into tiny pieces. Freeze for 30 minutes; scrape again. Repeat until granita resembles fluffy shaved ice, about 4 hours. Divide among bowls. Garnish with basil leaves and diced strawberries.
Preparation Bring 1 1/2 cups water to a boil in a small saucepan. Stir in hibiscus and basil sprig. Remove from heat, cover, and steep for 20 minutes. Strain through a fine-mesh sieve into a small bowl. Cover and chill hibiscus tea until cold, at least 1 hour. Meanwhile, blend quartered strawberries in a blender until finely puréed. Transfer to a large bowl; add tea, agave syrup, and 1 tablespoon lime juice. Season to taste, adding more agave and lime juice, if desired. Pour strawberry mixture into a 13x9x2" metal pan and freeze until top layer begins to harden, about 2 hours. Using a fork, scrape mixture to break frozen portions into tiny pieces. Freeze for 30 minutes; scrape again. Repeat until granita resembles fluffy shaved ice, about 4 hours. Divide among bowls. Garnish with basil leaves and diced strawberries.