1. Preheat oven to 200 C/180 degrees fan forced. Line 2 baking trays with non-stick baking paper.
2. Heat the oil in a frying pan over medium heat. Add onion. Cook for 3 minutes, or until soft. Transfer to a large bowl, allow to cool. Place bread into a small bowl. Pour over milk. Set aside for 5 minutes.
3. Add the bread mixture, sausage mince, parsley, 2 eggs, and salt and pepper to the onion. Using clean hands, mix until well combined.
4. Beat the remaining egg with a fork. Cut pastry sheets in half. Brush 1 long edge of 1 rectangle with beaten egg. Arrange filling in a sausage shape along opposite long edge. Roll up. Press to secure. Repeat with remaining pastry, egg and filling.
5. Brush the top of each roll with beaten egg. Sprinkle with sesame seeds. Cut each roll into 6. Place onto trays and bake for 15 minutes or until golden and puffed.
6. Meanwhile, combine the tomato sauce and sweet chilli sauce. Serve with sausage rolls.