Heat the oil in a small nonstick frying pan and cook the onion over a low heat for 8-10 minutes until tender.
Tip the fried onion into a mixing bowl and add the apple, sage, garlic and mustard.
Put the sausage meat in the bowl and mix with your hands then shape into 16 equal fat sausage shapes.
Unroll the pastry and cut into 16 equal rectangles.
Place one sausage down the left hand side of each piece of pastry, about 2cm from the edge – brush the other edge with beaten egg, then wrap the pastry over to enclose the sausage meat.
Press down and trim. Place on a baking tray, seam-side down, brush with beaten egg to glaze and slash the top of each roll a couple of times with a knife.
Bake for 35 minutes until golden brown and crisp. Delicious hot or cold.
