After the dough has doubled in size, punch it down and turn it onto a floured surface. Gently pat it down to a ½ inch ( 1 ¼ cm ) thickness.
Use a cookie cutter to cut out into circles. I used a 3 inch ( 7cround cutter.
Place the cutout shapes onto a tray or baking sheet and leave to rise for 15 minutes.
In a pot heat sufficient oil to deep fry the donuts. Heat the oil to a medium-low.
Fry the donuts, a few at a time until golden brown. The donuts should be fried for about 2 minutes on each side, to ensure that it is cooked well on the inside.
Roll the fried donuts in castor sugar and leave aside to cool for a few minutes.
Using a sharp knife make a hole in the side of the donut. Fit a pastry bag with a plain tip nozzle and fill with jam to pipe into the donut.
These donuts are best eaten fresh and on the same day that it has been made.