To begin, chill the veal, pork back fat, and mixing bowl in the refrigerator for 30 minutes. This step ensures the mixture remains cold, which is essential for achieving the right texture. Once chilled, combine the veal and pork back fat in the bowl with crushed ice.
Using a food processor or stand mixer with a paddle attachment, blend the meat mixture until smooth and emulsified. Work quickly to prevent the mixture from warming up. Add the chopped onion, lemon zest, salt, white pepper, mace, cardamom, and parsley, and blend until evenly incorporated.
Prepare the casings by soaking them in warm water for 15 minutes, then rinsing thoroughly under running water. Inspect for any tears and set aside. Use a sausage stuffer attachment or funnel to fill the casings with the meat mixture, taking care to avoid air pockets. Twist the sausages into 10-12 cm (4-5 inch) links.
Bring a large pot of water to a gentle simmer, maintaining a temperature of around 75°C (167°F). Avoid boiling, as this can cause the sausages to split. Lower the sausages into the water and poach for 20-25 minutes, ensuring they cook evenly.
While the sausages cook, prepare the accompaniments. Warm pretzels or bread rolls in the oven, and set out small bowls of Bavarian mustard. If serving with Weissbier, chill the beer until ready to serve.
Check the sausages for doneness by slicing one open; it should have a firm, pale interior. Remove the sausages from the water using a slotted spoon and place them on a serving platter.
For an authentic touch, serve the Weißwurst in a traditional terrine or deep bowl with a small amount of the poaching water. This keeps the sausages warm during serving and enhances presentation.
Serve the Weißwurst immediately with pretzels, mustard, and Weissbier if desired. Encourage diners to peel the casing before eating, as is customary. Garnish with fresh parsley for a touch of colour and tradition. Enjoy this iconic Bavarian delicacy with friends and family.