1: Put the oven on at 200C. Start by slicing one end off each sausage. Next, squeeze out the meat from within the sausage skin into a bowl.

2: Peel the onion, keeping it whole, and grate it. Then roughly grate the mushrooms and the potato. Add this all to a large bowl, along with the sausage meat, mustard, ketchup and a bit of salt and pepper. Give it a good mix. 

3: Unroll the puff pastry onto a clean flat surface, leaving the greaseproof paper underneath, so that the short side is closest to you. Spoon the sausage meat onto the pastry, leaving a gap at the bottom, and shape it into a long sausage shape that reaches the entire width of the pastry.

4: Starting from the bottom, pull the pastry up and over the sausage meat to join the pastry on the other side. Using a pastry brush or your fingers, brush the join with a little milk and push it down with your finger to seal. Brush the remaining pastry with a little more milk and continue to roll the sausage over until all the pastry is wrapped around. Finally, brush the edge of the pastry with milk to seal. 

5: Trim the greaseproof paper with a knife and place the sausage roll on a baking tray. Brush the top of the sausage roll with a bit more milk and gently cut a row of small lines along the length of the pastry, sprinkling a little curry powder on top.

6: Bake in the hot oven for 40-45 minutes, until golden brown and the sausage meat is cooked through. Take the sausage roll out of the oven and let it stand for a few minutes before slicing up. Serve with a dollop of brown sauce and tuck in!