Sorry: him again. There were three components to his perfect roast chicken meal on Tuesday night: the chicken, the roast potatoes, and the carrots. I wrote about the chicken yesterday, and I shall come to the carrots some other time. There are a couple of features of his roast potatoes I want to mention.
Blumenthal boiled his potatoes -- Maris Pipers -- until they were crumbly at the edges. As he said, you have to get the timing right: a minute later, and they would have turned into mash. But, as I have written, I parboil maincrop potatoes for just a few minutes, to get rid of some of the surface starch. The edges will crumble a little if you stir them in a hot, dry pan, and be crunchy once roasted.
On the other hand, Heston Blumenthal is a Michelin three-starred chef, and I am someone whose daughters accuse of being unable to cook frozen peas properly.
He boiled two batches of potatoes: one in salted and the other in unsalted water. The former batch was crunchier when roasted, he said. He did not explain why -- although he may do in his book. Turning to his guru -- and mine -- Harold McGee, I learn that the reason may be that salt speeds the softening of cells. The potatoes from the salted water were probably crumblier.
He roasted his potatoes in olive oil. I do too, sometimes; but more often I use sunflower oil -- frowned upon in some quarters.