Start by making the pastry. Rub the fat into the flour until it resembles breadcrumbs. Add a little water to the mixture and stir until the mixture starts to stick together in large lumps. Collect the dough mixture to form a ball and knead for a minute on a floured surface. Wrap the dough in cling film and place in fridge for 30 minutes.
Remove the dough/pastry from the fridge and cut into eight pieces. Roll each piece, on a floured surface, until it is the size and shape of you hand (extended, not clenched!). Place a few onion pieces in the centre of the rolled pastry.Take a pinch of cheese and place on top of the onion. Taking one end of the pastry, fold it over the filling onto the other end and press the edges down firmly with your fingertips. Cut off any excess pastry and put to one side. Repeat the process with the remaining seven pieces of pastry. You should have sufficient cut-offs to make a ‘bonus pasty’. Brush the pasties with the beaten egg and bake in the oven at 180°C (350°F) for about half an hour – or until the pastry turns golden in colour.