First, peel the potatoes & cut into evenly sized pieces (into quarters if the potatoes are large, 2-3 pieces if smaller).
Add the potatoes to a large saucepan & cover with cold water. Leave these to soak for at least an hour.
In a saucepan, place the butter, goose fat, oils, garlics & herbs. Set aside for later.
Preheat your oven to 220°c.
Drain the water off the potatoes & replace with fresh, cold water. Season the water generously with table salt. Place a lid on the pan.
Place the saucepan over a high heat & bring to the boil. Turn the heat down slightly & leave the potatoes to cook for 10-15 minutes, until the outside of the potatoes have started to soften.
Pour the potatoes into a colander & leave to drain for a minute.
Return the potatoes to the saucepan they were cooked in. Sprinkle over the semolina & cornflour, place the lid back on the pan & give the pan a good shake.
Using a pair of tongs, carefully transfer the potatoes to a large roasting tray. Leave to steam dry whilst you heat the fats up.
Place the saucepan of fats over a medium heat & cook for 4-5 minutes until melted & hot.
Pour the hot fat over the potatoes, making sure that each potato gets covered. Season generously with Maldon salt & freshly cracked black pepper.
Roast the potatoes in the preheated oven for around 45 minutes or until crispy & a deep golden brown colour. Make sure to flip the potatoes over every 15-20 minutes so that they colour evenly.
Once cooked, transfer the roast potatoes to a serving dish & season again with salt.