Mix beef, mustard seed, garlic powder, curing mixture, pepper flakes, salt, cayenne, and liquid smoke together in a large bowl until well combined. Cover with plastic, and refrigerate for three days, mixing well once a day.

On the fourth day, preheat the oven to 200 degrees F (100 degrees C). Line a sheet pan with a wire rack.

Shape the mixture into five logs; place logs onto the wire rack.

Transfer the rack and sheet pan into the preheated oven and bake for 8 hours. Remove from the oven and transfer sausages to paper towels to cool. Let cool completely, about 1 hour, then wrap logs individually in plastic wrap. Refrigerate for at least 3 hours before slicing.