Preheat the oven to 400F.
Cook the diced onions until they turn translucent.
Mix the sausage meat with the onions, breadcrumbs, Worchester sauce, and mustard together. You can season the sausage meat mixture to your liking with salt, pepper, and any other spices you would like.
Roll out the puff pastry till the thickness of a coin.
Line the sausage meat in the middle of the puff pastry roll.
Egg wash the top end of the pastry and roll the sausage meat so that the pastry wraps around the sausage meat. Egg wash the end of the puff pastry to seal.
Slice the sausage roll into 1 1/2 inch slices.
Egg wash the top of the sausage roll and score the top of the sausage roll. Garnish with some sesame seeds.
Bake for 15-20 minutes or until golden brown.