Preheat the oven to 350º F (180º C). Grease bottom and sides of the ring mold baking pan.

In a large bowl, soak the stale bread in the warm milk until bread is softened and the milk is almost cool. In a blender, blend the mixture of bread and milk, the eggs, sugar, cinnamon, vanilla, and wine. Then, stir in the lemon zest and raisins.

Pour the blended bread mixture into the pan. Place ring mold pan in a larger, rectangular baking pan, and fill with boiling water to come halfway up the side of the ring mold pan (Bain-Marie). Bake for about 45-55 minutes, or until a toothpick inserted in the pudding comes out clean.

Let pudding cool down on a rack. When it is slightly warm, run a small metallic icing spatula or knife around the edges of the pan to loosen the pudding. Invert onto a serving plate. Cover and refrigerate for at least 4 hours. Serve with the port sauce on top.

To prepare the Port wine sauce: In a heavy small saucepan, stir Port, lemon juice, and sugar over low heat until sugar dissolves. Increase heat to medium-high and boil until mixture is reduced to 1/2 cup, about 10-15 minutes. Combine water and cornstarch well in a small bowl. Whisk into Port mixture and boil until slightly thickened, stirring constantly for approximately 2 minutes. Let cool and pour over the Coimbra-style bread pudding.