1. In a medium saucepan, combine the wine, star anise, cinnamon and allspice. Simmer over moderate heat for 5 minutes. Cover and remove from the heat. Let the wine steep, covered, for 20 minutes.
2. Whisk the sugar into the passion fruit juice until dissolved.
3. Just before serving, reheat the wine, but do not boil. Stir in the passion fruit juice. Place an orange slice in each of 10 brandy snifters and ladle in the wine, leaving the spices behind; serve.
Notes: To make fresh passion fruit juice, cut the fruit in half crosswise. Working over a coarse strainer set over a bowl, use a small spoon to scrape the seeds and juice into the strainer; press firmly to extract as much juice as possible. Eight small passion fruits yield 1/4 cup of juice, which can be frozen for up to 6 months.