Step 1 Cut the pork skin into 2-inch pieces. Cook it in boiling water for 40 minutes, or until it offers little resistance to the point of a knife. Drain and refresh under cold water, then grind it through a three-sixteenth-inch plate. Weigh the pork skin -- you will have less than you started with due to shrinkage. If you have less than 13 ounces, open the grinder plate, remove any skin remaining and chop it fine by hand. Place it on a plate and refrigerate.
Step 2 Cut the pork and fatback into rough 1-inch chunks and lay the pieces on a baking tray. Cover the tray with foil and place it in the freezer. Make sure the meat and fat are very cold before grinding (32 degrees is ideal; the meat will feel nearly frozen).
Step 3When the meat and fat are very well chilled, transfer the pieces to a mixing bowl. Break the skin (which will have congealed) into small pieces and add it to the bowl along with the salt, pepper, sage, cayenne, garlic, aniseed and sugar. Mix quickly with a spatula to evenly distribute the ingredients.
Step 4Grind the mixture once through a 3/8-inch plate into a large chilled bowl; if it is warm in your kitchen, place ice under the bowl. Use a large spatula to blend the ingredients. As you mix you will notice the meat becoming firm and compact. When the mixture is thoroughly combined and feels quite sticky, stop mixing.
Step 5Flush the casings under running water. Stuff the sausage into the casings and twirl the sausages off to 3 1/2- to 4-inch lengths. Refrigerate the sausages, uncovered, until they lose their surface moisture. They may be kept covered in the refrigerator for up to 4 days. Or wrap them well and store them in the freezer up to several months.