Adapted from joannagoddard.blogspot.com
large russet potatoes, peeled
cup canola or sunflower oil
springs rosemary, leaves picked
Preheat the oven to 475F. Cut the potatoes in half lengthways, then again crosswise. Half-fill a large deep saucepan with cold water, add a pinch of salt and the potato pieces. Bring to a boil over high heat, then turn the heat down to medium and simmer for 15-20 minutes or until a knife can be inserted easily into the potatoes but there's just a little resistance in the center. You want to just par-boil the potatoes; if you overcook them at this stage, they will become too mushy. Drain the potatoes in a colander, then return them to the saucepan. Cover with the lid and give the pan a really good shake to fluff up the potatoes; these soft, loose edges will become really crispy during roasting. If you want, you can scrape the edges and tops of the potatoes with a fork to create even more fluffy bits. Add the oil to a deep roasting tin and place in the oven for 10 minutes until smoking hot. Remove the roasting tin and turn the oven temperature down to 425F. Carefully add the potatoes to the hot oil, then sprinkle over the rosemary leaves and crumble a bit of sea salt on top. Return the tin to the hot oven and roast for 50 minutes to 1 hour, or until the potatoes are really crispy and a gorgeous golden brown. Feel free to turn the spuds halfway through to ensure even browning. Serve piping hot with an extra sprinkle of sea salt.