PreparationMake buttermilk puddings: Sprinkle gelatin over 1/4 cup milk in a small bowl and let soften 1 minute. Scrape seeds from vanilla bean into a small heavy saucepan and add pod. Add remaining 3/4 cup milk and sugar and bring just to a boil over medium heat, stirring until sugar has dissolved. Remove from heat. Add gelatin mixture to hot milk mixture, stirring until dissolved. Quick- chill in an ice bath, stirring occasionally, until cold but not thickened, about 5 minutes. Stir in buttermilk, then strain through a fine-mesh sieve into a large glass measure, discarding solids. Pour into bowls and chill until set, at least 8 hours. Make sauce: Bring wine, water, sugar, zests, and bay leaf to a boil in a small heavy saucepan over medium heat, stirring until sugar has dissolved, then boil until reduced to about 1/3 cup, about 10 minutes. Add strawberries and simmer 5 minutes. Discard zests and bay leaf, then purée strawberry mixture in a blender until smooth (use caution when blending hot liquids). Force through clean fine-mesh sieve and discard solids. Chill sauce, stirring occasionally, until cold, about 1 hour. To serve: Spoon sauce over puddings and top with remaining berries. Cooks' note:Buttermilk puddings and sauce can be made 3 days ahead and chilled separately.