Rub the margarine into the flour using fingertips, until the mixture resembles fine, dry breadcrumbs. Mix together with enough cold water to form a soft but not sticky dough. Knead dough gently on a lightly floured surface and divide into 4 equal sized pieces.
Roll out each piece of dough into a circle shape, about 1/2 cm in thickness.
Mix together the potato, onion, carrot, corn kernels, green beans and quorn mince and crumble the stock cube into the mixture.
Place a small amount of filling onto each pastry circle, using your fingers dampen the edge of the pastry with water and bring the edges together. Seal well.
Place the pasties onto a greased baking tray and glaze with milk. Then with a fork, make little holes into the side of the pasties. This will prevent them from bursting open.
Bake for 10 minutes at 220 degrees C, then reduce the temperature to 180 degrees C and bake for a further 20 minutes.
When mixing the water in to form a dough, pour the water in a bit at a time, to make sure the dough doesn't turn out sticky.
If you are serving it to a non-vegetarian, you may use the same amount of chicken mince, turkey, lamb or pork.