Preheat the oven to 350°F (175°C).
In a mixing bowl, combine ground pork, minced garlic, thyme, marjoram, basil, rosemary, beaten egg, breadcrumbs, kosher salt, and pepper. Mix well until all ingredients are evenly incorporated.
Cut the puff pastry lengthways into two long, even rectangles.
Spread a thin layer of Ballymaloe Relish on each rectangle, using roughly 2 1/2 tablespoons on each rectangle.
Take the sausage mixture and roll it into a log, ensuring it's the length of the pastry. Place the sausage log lengthways along the middle of each pastry rectangle.
In a small bowl, beat the egg. Brush the bottom portion of the pastry with the beaten egg, then fold the back side of the pastry over the filling, wrapping it inside to form a long tube. Press down with your fingers or the edge of a spoon to seal.
Cut the long rolls into thirds and space them out on a parchment paper-lined baking tray.
Brush the tops of the rolls with the remaining egg wash.
Place the baking tray in the preheated oven and bake for 25-30 minutes or until the pastry is puffed, golden, and the sausage is cooked through.
Serve the sausage rolls with a side of Ballymaloe Relish or brown sauce, such as HP sauce. Enjoy!