Ingredients
8 cups 3/4-inch seedless watermelon cubes (from 1/2 small watermelon, rind removed), plus more for garnish
Scant 2 1/4 teaspoons unflavored gelatin (one 1/4-ounce envelope)
1/4 cup cold water
1/4 teaspoon coarse salt
1 1/2 teaspoons fresh lemon juice
Rose Hip-Hibiscus “Ice Cubes”(optional)
Mint or basil sprigs, for garnish
Preparation
Puree watermelon cubes in a blender or food processor until smooth. Press through a fine sieve into a large bowl and discard solids. Measure 3 cups strained juice.
Prepare an ice-water bath. Sprinkle gelatin over cold water, and let stand until softened, about 5 minutes. Bring 1/2 cup watermelon juice and salt to a simmer in a small saucepan over medium-high heat. Add softened gelatin, stirring to dissolve. Strain into a bowl set in ice water bath. Stir in remaining 2 1/2 cups watermelon juice and the lemon juice.
Let stand, stirring often, until just beginning to gel, 15 to 20 minutes. Divide among 4 glasses. Garnish with watermelon cubes. Refrigerate until set, at least 2 hours or up to overnight. Top with rose hip-hibiscus “ice cubes” if desired, and garnish with mint or basil sprigs.