Combine the pork shoulder with vinegar, sugar, soy sauces, garlic and bay leaves in a large bowl.
Cover and refrigerate overnight to marinate.
Drain marinade off into a medium saucepan and place over a medium-low heat.
Bring to a simmer and cook until reduced by half, then set aside to cool.
Using a meat grinder, push pork through the grinder on a coarse blade first, then a finer blade to finish.
Place minced meat in a large bowl and mix in reduced marinade, eggs, and rice. Mix until very well combined and season with salt and pepper.
Preheat oven to 190°C fan forced (375°F). Place a seasoned cast iron pan in the oven to preheat.
Place pastry rolls on a clean work surface, unroll and slice in half to make 4 pieces.
Divide mince mixture into 4 portions and form into tight logs the length of the longer side of the pastry.
Place a portion down the centre of the pastry and brush both long edges with some of the extra beaten egg.
Roll pastry into a log with the seal on the bottom, then brush the tops with more egg.
Place 2 logs on a sheet of baking paper and lightly make an indent with a knife in the tops to divide the log into 3 portions.
Transfer the rolls to the heated tray and bake for 35-40 mins, until deep golden brown.
Repeat with the remaining logs, then slice into portions and serve with banana ketchup.
