Method
In a food processor place the peeled and halved onions and turn on to chop fine. Add the bread crumbs. Add the mince and blend well on high until it looks like sausage. Add the potato,basil and garlic and salt and pepper blend for a furthur 5 or so seconds. This can all be done by hand and mixed in a bowl if you don't have a machine.
Place the pastry out on the bench and roll quite thin about 3mm into a rectangular shape about 12cm by 40cm( if using Bells it should be thin enough). Place the sausage meat along the edge of the pastry to make it look like a long sausage. Roll the pastry over until the meat is hidden and the pastry overlaps by at least 1cm then cut any excess pastry away. You should now have a long sausage roll with a bit of pastry left over. You may need to moisten the pastry where it overlaps so that it seals. Repeat this process until all the meat filling is used. You can freeze these uncooked. Take the long sausage roll and cut into desired lengths and place on a baking tray with seald pastry edge facing down and brush the tops with a little milk. Put into a preheated oven 220°c for 10 minutes then reduce the heat to 180°c for 10 minutes or until golden. Be mindful it will look slightly pink but this is because you have used beef mince.