Dice the wild boar meat and fatback into cubes that will easily fit into a meat grinder. Partially freeze the meat and fatback to facilitate grinding, about 1 hour.
While your meat is freezing, toast the fennel seeds, anise seeds, and peppercorns in a dry pan on the stovetop until fragrant, and grind them in a spice grinder. Mix the ground fennel seeds, anise seeds and peppercorns with the sage, thyme, salt, paprika, cayenne, garlic and citrus zests in a large bowl.
When the meat and fatback are almost frozen, remove them from the freezer, and mix them with the other ingredients. Grind everything together through a medium-size die. Add a couple ice cubes at the end of the grinding to push out the last bit of meat in your grinder. Mix the meat vigorously in a stand mixer for a few minutes until the whole batch is very sticky. Pump the mixture into the sausage casings, and twist to create links of your preferred size (8 inches is ideal).
Keep the meat, fatback and tools as cold as possible while grinding.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.