Prepare the Filling:

1. Cook the Onions and Garlic: Heat a tablespoon of olive oil in a frying pan over medium heat. Add the finely chopped onion and cook for about 5 minutes, until softened and lightly browned. Add the minced garlic and cook for another 30 seconds, stirring frequently to prevent burning. Remove from heat and set aside to cool slightly.
2. Mix the Sausage Filling: In a large mixing bowl, combine the halal sausage meat, cooked onions, garlic, parsley, thyme, salt, pepper, and optional chili flakes. Use your hands or a spoon to mix everything together until well combined. If you’d like, you can also add a little grated cheese or vegetables (like finely chopped spinach or mushrooms) to the mixture for extra flavor.

Assemble the Sausage Rolls:

3. Preheat the Oven: Preheat your oven to 400°F (200°C). Line a baking tray with parchment paper for easy cleanup.
4. Roll Out the Pastry: If you’re using store-bought puff pastry, roll it out on a lightly floured surface to smooth out the creases and ensure an even thickness. If using homemade puff pastry, ensure it is chilled and then roll it out into a rectangular shape about 1/8-inch thick.
5. Form the Sausage Rolls: Cut the puff pastry into rectangles (about 4-5 inches wide and 8 inches long). Place a generous amount of the sausage mixture along the center of each pastry rectangle. Be sure to leave some space at the edges for sealing.
6. Roll the Pastry: Carefully fold the sides of the pastry over the filling and then roll the pastry into a log shape. Seal the edge by pressing it gently with your fingers or a fork.

Bake the Sausage Rolls:

7. Prepare the Egg Wash: In a small bowl, beat the egg and milk together. Brush the tops of the sausage rolls with the egg wash, giving them a glossy, golden finish once baked.
8. Bake: Place the sausage rolls on the prepared baking tray and bake for 25-30 minutes, or until the pastry is golden brown and puffed up, and the filling is fully cooked. You can check for doneness by cutting one open to ensure there’s no raw sausage inside.

Cool and Serve:

9. Let Cool: Once baked, remove the sausage rolls from the oven and let them cool for a few minutes before serving. These rolls are delicious both hot and at room temperature.