Also: Duck or goose fat gets the crispiest potatoes.
As mentioned above, parboiling is also important.

After you've done that, rough up the surface of the potatoes with a fork. It increases the surface area, allowing more oil-to-starch contact.
( gronkpan https://twitter.com/VomitingLarry, Fri 19 Sep 2008, 15:53, 1 reply, 16 years ago)

Duck fat is indeed good for it
But don't buy rendered duck or goose fat, as this is produced by boiling remnants of the animal to seperate the fat.

Best thing to do is to buy a fatty duck, make holes all over the skin with a sharp fork, then roast it with some wine and whatever seasoning / stuffing.

When it's done, pour off all the juices and fat into a jug / bowl and leave to cool before putting it in the fridge. All the juices, wine and bits of food will sink to the bottom to form a hard jelly, while the fat will sit at the top, pure and white.

The difference is, this fat tastes AMAZING. Rendered fat will make your potatos crispy, but fat produced from roasting will make you cream your pants, trust me.

Also agree with the points about parboiling / roughing spuds / getting teh fat as hot as poss.
(prescottspies eating pies to save the nation, Sat 20 Sep 2008, 12:19, Reply)