Step #1 Combine sugar, wine & water In a large-ish heavey-based pan, without boiling, stir over heat, until sugar dissolves.
Step #2 Bring to boil, simmer, for about 20 mins or until syrup is thickened slightly (syrup must not change colour), uncovered, without stirring, cool to about room temp.
Step #3 Stir in juices & bitters.
Step #4 Pour mixture into 23cm square cake pan, cover with foil wrap & freeze until firm.
Step #5 Beat lemon mixture in large bowl with electric mixer until smooth.
Step #6 Beat egg whites in a small bowl with an electric mixer until firm peaks form.
Step #7 Fold egg whites into lemon mixture in 2 batches.
Step #8 Return mixture to cake pan, cover & freeze until firm.