Squeeze the sausage meat into a bowl.
Peel and finely chop the onion.
Put the oil in a pan over a medium heat.
Add the lardons and onion and soften for a few minutes, without colouring.
Mix the onions and bacon with the sausage meat and add the pepper and tarragon.
Roughly divide the mixture into 2 in the bowl.
Carefully roll out the pastry and leave it on the parchment paper it is wrapped in.
Cut in half lengthways.
Arrange half of the chicken sausage roll mixture in an even sausage in the middle of the pastry.
Beat the egg and use a pastry brush to moisten the long edge at the top.
Roll the pastry over the sausage meat and press down gently to seal the join.
Cut the roll in half and cut each half into 4 rolls.
Repeat with the remaining pastry and sausage meat.
Transfer the chicken and bacon sausage rolls to a baking tray lined with silicon or baking parchment.
Glaze with the remaining beaten egg and sprinkle over some sesame seeds.
Preheat the oven to 200 C / 400 F / 180 FAN / Gas 6 and bake for 20 - 25 minutes until golden.
Leave to cool for afew minutes then transfer to a wire rack.
They are best served still warm from the oven.