Before Heston Blumenthal came up with his triple-cooked chips, the most widely recommended chip recipe involved double-cooking. You cook the potatoes at about 140C, in effect boiling them; you take them out of the oil, turn up the heat until the oil reaches about 190C, and return the potatoes to the pan for browning.
I am not going to bother with the Blumenthal version; and my recipe for fried potatoes, which are just like chips only cubed, has convinced me that the double-cooking method can be simplified. You do not need a thermometer, and you do not need to remove the potatoes from the pan half way through cooking. Also, you can fry a surprisingly large quantity of chips with success, rather than doing it in batches. This weekend, I managed six medium potatoes-worth, for four people.
I used a stock pot/pasta pan with a capacity of four litres, and I poured a litre bottle of sunflower oil into it.
Warm the pan with the oil above a low to medium heat.
Peel the potatoes, and cut them lengthwise into wedges about 1cm thick; or, if they are big, cut them in half crosswise, and then lengthwise into wedges. Cut these wedges lengthwise into chips, and put them in a bowl of water. Rub them a little to disperse some of the surface starch.
If you do not have a thermometer (or a chip pan), test the heat of the oil with a little cube of bread. It is ready when the bread sizzles gently on impact.
Remove the chips in batches from the water to paper towels, and dry them. You do not have to be too thorough; but if you leave a lot of water on them, they will cause the oil to bubble up alarmingly. Add them to the oil as you go. Regulate the heat if necessary to keep them simmering in the oil.
After 10 minutes, simply increase the heat -- I turned my flame (one of the back rings, and not the most powerful) to full. The chips should take about 10 minutes further to brown. Lift them from the oil with a slotted spoon to colanders lined with paper towels.
These chips, made with King Edwards, were superb: crisp outside, creamy inside. I do not think that any more elaborate method is necessary.