I love Serious Eats, especially their food lab with Kenji! He develops delicious and amazing recipes like these ultra crispy roast potatoes and then explains why they work so well! These potatoes turn out extra crispy because you build up a layer of gelatinized starch by par-boiling them in acidic water first and then increasing their surface area by tossing them in a bowl with a metal spoon. Talk about cool! (And nerdy, but hey, I'm a chemist!) Then you roast them with fat, salt, pepper and thyme. These definitely were the most crispy roast potatoes I've ever had. I didn't have the recommended duck fat, so I went with bacon fat instead, which worked well. Next time I'll probably try olive oil to be nicer to my heart.