So McDonald's does indeed use a double fry method, but it's far from the traditional one. Rather than a slow low temperature fry for the first round, the fries get dunked into very hot oil for only 50 seconds (the second fry is then carried out at the actual location). In addition to this, the potatoes get a pre-fry blanching step in hot water.

The Burger Lab: How to Make Perfect Thin and Crisp French Fries | A Hamburger Today Saturday, December 28, 2013 @ 10:01pm