- 1 (.25 ounce) envelope gelatin
- 1 1/2 cups sugar
- 4 cups unstrained ruby grapefruit juice (see Note)
- 2 tablespoons sweet vermouth (or grapefruit juice)
- 2 tablespoons grenadine syrup (or grapefruit juice)
- Grapefruit segments and rinsed citrus or mint leaves (optional)
- In a 2- to 3-quart pan, stir together gelatin and sugar; add 2 cups water and bring to a boil over high heat. Stir until sugar dissolves. Let cool. Add grapefruit juice, vermouth, and grenadine syrup.
- Pour mixture into a metal pan (about 9 by 13 inches); cover. Freeze until solid, at least 6 hours or up to 1 month.
- Break into small chunks and whirl in a food processor or beat with a mixer until a smooth slush forms. Return to freezer for 20 to 30 minutes.
- Serve sorbet softly frozen; spoon into chilled dishes and garnish with grapefruit segments and citrus leaves. If stored, sorbet gets very hard; beat again for smooth texture.