Frozen sorbet lemons

Cut the top (or the bottom, whichever is prettier) from each large Sorrento lemon to make a lid, and set aside. Trim the other end of the lemon flat so it can sit steadily on a plate. Using a small, serrated knife, cut out the lemon flesh and squeeze into a jug, keeping the shells. Put the squeezed flesh in a sieve and press over the jug to extract the last of the juice. Press out any juice from the lemon shells and lids, too (you'll need about 200ml juice in total).

Put the sugar, 150ml cold water and the lemon zest into a medium saucepan. Heat gently until the sugar dissolves, then bring to a gentle boil. Boil the mixture for 2 minutes, then take the pan off the heat and stir in the lemon juice. Transfer to a shallow freezer proof container; leave to cool to room temperature before freezing solid (about 6 hours).

When the sorbet is completely frozen, cut it into big chunks and put them in a food processor, Whizz briefly, adding the egg white, until you have a pale and fluffy mixture. Return the sorbet to the original freezer proof container and freeze again until firm ( about 2 hours).

Scoop the sorbet straight from the freezer and push it into the frozen lemon shells. Be generous and make them overflow. Top each with a lid, then put back in the freezer until ready to enjoy.