I worked the fryer at 5 guys and their method is to double fry them. I would drop the fries in for 3 minutes and take them out for 1 then drop them back in again for another minute. Crisps the outside and leaves inside fluffy.
We also soaked the potatoes for several hours to de starch them before frying
We also soaked the potatoes for several hours to de starch them before frying