1. Sprinkle gelatin over cold water; let stand 10 minutes.
2. Meanwhile, combine cream and next 3 ingredients in a medium saucepan over medium heat. Split vanilla bean; scrape seeds into cream mixture, and place bean in mixture.
3. Cook over medium heat, stirring constantly, 5 minutes or just until mixture begins to boil. Remove from heat; immediately stir in gelatin mixture until smooth. Let stand 5 minutes.
4. Discard tea bags and vanilla bean. Stir in buttermilk and salt. Strain into a heatproof glass measuring cup. Divide among 8 (6-oz.) glasses. Cover and chill 24 hours. Serve with Berry Sauce.