Stroll around the beautiful cities of Lisbon or Bordeaux, and it is likely that you will be as enchanted by the beautiful pastries as you will be by the wine. Pastéis de Nata, the delicious custard tarts which date back to before the 18th century, are thought to have been invented at the Jeronimos Monastery in the Confeitaria de Belém area of Lisbon, and cannelés, the spool-sized pastries which taste of custard and rum, are attributed to the city nuns from Saint Eulalia church. Apart from divine intervention, they both have something else in common. They are a by-product of winemaking. Many winemakers use egg whites to ‘fine’ wine, port and sherry, which is a way of clarifying the wines before they are bottled, and historically the surplus egg yolks were donated to convents who used them to make pastries and desserts like tocino del cielo. The egg white attracts and catches any cloudy particles in the wine, and when this debris is removed, all the egg white goes with it, so there isn’t a trace of it left in the wine. However, because it is used in the process, it doesn’t comply with the vegan diet. It’s not the only animal-related product which is u...