Reserve 1 1/2 cups of the fresh berries to fill the sherbet receptacles at serving time. Put the 1 1/2 pounds of fresh or defrosted frozen berries in the bowl of a food processor with the preserves, and process until liquefied, or push through a food mill fitted with the fine screen. Strain through a sieve to remove any remaining seeds. You should have about 3 1/2 cups of raspberry coulis or puree. Reserve 1 1/2 cups for the sauce, and add the brandy to this sauce. Refrigerate until serving time. Add the lemon juice and water to the remaining 2 cups to be used for the sherbet, and freeze, covered with plastic wrap, in a stainless-steel bowl for about 3 hours, until frozen but not too hard.
Break the frozen sherbet into pieces with a spoon, and dump them into the bowl of a food processor. Emulsify in several batches or all together until the sherbet becomes creamy and lighter in color. It should not be processed much more than 30 seconds; by then, it will have liquefied a little. Return the puree to the stainless-steel bowl, cover, and put back in the freezer for a few hours.
To make the sherbet receptacles, line six 1-cup glass bowls with plastic wrap, and spoon a sizable scoop of sherbet inside each.
With a spoon, press on the center of each scoop to hollow it out, and push the sherbet up around the sides of the cup to create a "nest" in the center. Fold the plastic-wrap edges over the sherbet, and place in the freezer for a few hours, until hard. (This can be done several days ahead).
To serve: Remove the frozen sherbet receptacles from the freezer, and pull back the plastic wrap to expose the center. Fill each with about 1/4 cup fresh raspberries.
Invert the sherbet cups carefully in the center of six dessert plates, and remove the plastic wrap. Pour the raspberry sauce around the cups, decorate with lemon peel, mint, or edible flowers, and serve.