Place raspberries in a blender container or food processor bowl. Cover and blend or process until pureed. Sieve puree to remove seeds. Discard seeds. (You should have about 1-1/4 cups puree.) Stir together the puree, sugar, orange juice, and snipped lemon thyme in a small mixing bowl.
Pour mixture into a nonmetal freezer container. Cover and freeze for several hours or until almost firm. Break mixture into small chunks; transfer to a chilled bowl. Beat with an electric mixer until smooth but not melted. Return to container. Cover and freeze for 6 hours or until firm.
To serve, scoop mixture into individual dessert dishes. If desired, garnish each serving with a lemon thyme sprig. Makes about 2 cups or 4 servings.