In the bowl of a stand mixer fitted with a paddle attachment, combine butter, suet, flour, and salt until pea-sized pieces form.
Slowly stream in 250 grams ice water until dough comes together and is homogenous.
Tightly wrap dough in plastic wrap and refrigerate overnight.
In a large bowl, add pork, eggs, salt, chile flakes, white pepper, and fennel seeds.
Using gloved hands, mix until all ingredients are thoroughly and evenly combined.
Cover and refrigerate overnight.
The next day, chill and prepare a meat grinder with a small die.
Pass mixture through grinder.
In a large bowl, combine pork mixture with maple syrup.
Transfer to a piping bag and refrigerate.
Heat oven to 375°F.
On a lightly floured work surface, roll out Suet Pastry and fold once.
Roll out into a large ¼-inch-thick rectangle.
Place the cold pastry onto a prepared baking sheet.
Pipe a generous log of Pork Sausage across the bottom edge of the rectangle.
Fold the pastry over the meat filling to form a long roll.
When the bottom edge meets the top edge, run a sharp knife along the dough to evenly cut.
Using wet hands, seal the roll and cut into 3-inch long pieces.
Brush each roll with egg wash and sprinkle with sea salt and fennel seeds.
Bake 30 minutes.
Serve warm.
