You need to chill them. I stick mine outside to cool. Give them a good parboil so theyre a bit crumbly, bash them up in the pan a bit
Then put your roasting tray with fat on the hob and heat it so it's really hot. Preferably fat from youre beef or whatever.
Tip the potatoes in and keep on the hob whilst you're coating with the oil. Add a few cloves of garlic if you want to.
Add salt.
Stick in the oven.on a high heat, turn down to gas mark 6 after 20 mins or so.
Then you'll have the world's best toastie.