Peel and cut your potatoes in half. Cut lengthways to maximise a crispy crust.
Put the potatoes into cold water in a saucepan, add salt and bring to the boil. Let your potatoes parboil for 6 minutes.
Drain the potatoes in a colander, then tip them back into the empty dry saucepan.
Replace the lid and give the pan a quick shake before sprinkling the potatoes with semolina.
With the lid on, shake the potatoes around to coat them well. Make sure you hold the lid down tightly.
Transfer the potatoes to your slow cooker, turning them in the hot oil and butter.
Place 2 large sheets of kitchen roll over the top of your slow cooker pot and secure in place with your lid.
Cook for 3 hours on high, turning halfway through cooking.
Sprinkle with sea salt and a few fresh parsley leaves to serve.