Place the chocolate shell tubes on a flat sheet pan lined with a nonstick rubber mat in a standing position in a freezer; they should still be inside the PVC tubes for stability.
Remove the acetate from the bergamot sorbet tubes; trim the ends if necessary so that they are 12.5cm/5in long.
Combine the Earl Grey tea with the egg white powder in the bowl of an electric mixer fitted with a whip attachment and mix on low speed.
Meanwhile, make a syrup with the sugar and the water by combining them in a small sauce pot and bringing them to a boil. Turn off the heat and make sure that all of the sugar has dissolved. Add the gelatin and stir until it has dissolved. Let it cool to room temperature.
Add this syrup to the tea and egg white powder mixture when it has reached half its maximum volume (it will have tripled in volume when it is at half the maximum volume). Pour the liquid down the side of the bowl as the mixer whips.
Continue to whip on high speed until the mixture reaches full volume. It will have increased in volume six times from its original volume.
Transfer the mixture into a piping bag and pipe it into the chocolate shell tubes to fill three-quarters of the way up.
Insert a frozen bergamot sorbet tube into the center of each chocolate shell tube, going through the foam.
Insert a rectangle of Earl Grey génoise next to the sorbet.
Even out the foam at the top of the shell tube with an offset spatula.
Return to the freezer to harden. Reserve frozen during service, keeping the exposed surface covered. Discard after 4 days.