For the sausage: Put the grinder attachments in the freezer so they are cold when you begin. Cut the pork into 1-inch cubes, then arrange on a baking sheet in a single layer and pop into the freezer for 10 minutes. It is important to make sure that all the ingredients and equipment are very cold to make the grinding easier and yield a smoother texture.
Put the chicken stock in a large pot and heat to steam but not simmer. Line a sheet pan with paper towels and set aside.
Place the bowl from an electric stand mixer under the grinder. Put the chilled attachments in place, using a medium-hole grinding plate. Run the cubed pork through the grinder, working carefully and quickly. We want the meat to stay as cold as possible.
Gently spread the ground meat all over the bottom of the bowl and up the sides a little. This will help you to distribute the seasonings evenly. Sprinkle with the salt, Parmigiano-Reggiano, milk powder, fennel seeds and red pepper flakes. Add the garlic. Place the mixer bowl on the machine fitted with the paddle attachment. Turn the machine to low and pour the wine down the side of the bowl to incorporate, about 1 minute. Increase the speed to medium and beat until the mixture becomes sticky, 2 to 3 minutes. Stop the machine.
To test for seasoning, make 1 small sausage patty, about 2 inches in diameter. Heat the canola oil in a small skillet over high heat. When the oil begins to smoke lightly, shut off the heat (to avoid splattering) and add the meat patty. Turn the heat back on and brown on both sides for a few minutes until cooked through but still pink in the middle. Taste the cooked sausage for seasoning and adjust the meat mixture if necessary.
Place the hog casings gently on the extruder tube of the sausage maker. Imagine you are gently putting a sock on your foot and push several layers of the casing to wrap around the tube. Don't let the casings bunch up or become too tight. Start the extruder and load the meat mix into the top. Let a little of the meat go into the casing, taking care that there are no gaps or pockets. Press the casing around the meat so they hug each other. Go slowly. Stop every 3 1/2 to 4 inches or so, cut the end closest to the extruder, twist and tie off the ends with twine to make a link. If the casing breaks, take the meat out, put a fresh casing on the extruder and start again.
Gently drop the sausages into the hot, steaming stock in a single layer. Let them cook gently without boiling, turning them halfway through, until no longer pink in the middle, 3 to 5 minutes. Transfer the cooked sausages to the sheet tray lined with paper towels and let them cool and dry for 10 to 15 minutes.
For the slaw: Mix the mayonnaise, mustard, vinegar, hot sauce and Worcestershire in a bowl. Add the cabbage and stir to coat. Season with salt and stir in the parsley.
For the honey-mustard sauce: Whisk the mustard and honey together in a bowl. Season with salt to taste.
Heat a grill pan to medium high. Coat the sausages in a small amount of oil and lay them on the grill pan. Grill on both sides, 3 to 5 minutes total. Drizzle oil over the inside of the rolls and toast on both sides over medium-high heat on the grill pan.
Place a grilled sausage link on a toasted roll, spread with honey mustard and top with the cabbage slaw. Garnish with more chopped parsley.