Preheat the oven to 200°C fan forced (390°F).
Place potatoes on an oven tray lined with baking paper.
Prick several times with a fork then bake for 35 minutes, until almost tender.
Set aside until cool enough to handle.
Slice the potatoes into quarters and scoop out the flesh in a large chunk.
Chill until very cold.
Reserve the potato skins for another use.
Grate the potatoes into a large bowl.
Mix in the cornflour, butter, garlic powder and chorizo.
Season well with salt and pepper.
Mix well until the potatoes come together like a dough.
Slice mozzarella into 6 pieces, approximately 3cm x 6cm x ½ cm.
Divide potato mixture into 6 portions and form into balls.
Divide each into 2 and flatten 1 portion out in the palm of your hand, then top with a piece of cheese and cover with the other potato portion.
Mould into an oval shape and flatten to 3cm high, smoothing the edges.
Transfer to a lined tray and freeze for 30 minutes.
Heat the oil in a deep frying pan to 140°C (285°F).
Gently lower the hash browns in batches into the oil and cook for 3 minutes.
Carefully transfer back to the tray and chill again until very cold.
Increase oil temperature to 180°C (355°F).
Cook hash browns again, in batches, for 5 minutes, turning to brown evenly, until very crisp and dark golden.
Drain on a wire rack over a tray, season with salt and serve.
