Ingredients

　　4 cups picked over blueberries

　　1 cup sugar

　　the zest of 1 navel orange, removed in strips with a vegetable peeler

　　2 tablespoons Grand Marnier, or other orange-flavored liqueur

　　3 tablespoons fresh lemon juice

　　1/2 teaspoon vanilla

　　1/8 teaspoon salt

　　2 cups heavy cream

　　1 cup half-and-half

　　In a large saucepan combine the blueberries, the sugar, the zest, and 1/4 cup water, boil the mixture, covered, for 5 minutes, stirring occasionally, and simmer it, uncovered, for 5 minutes. Discard the zest and purée the mixture in batches in a blender or food processor. Transfer the purée to a bowl and whisk in the Grand Marnier, the lemon juice, the vanilla, the salt, the heavy cream, and the half-and-half. Force the mixture through a very fine sieve set over another bowl and chill it, covered, for 1 hour, or until it is cold. Freeze the mixture in an ice-cream freezer according to the manufacturer's instructions.