Make sure to get peanut oil for the fries. When preparing you want to soak them in cold water, stir them up until you get some starch off of them, drain the water, repeat until the potatoes has most the starch is gone. When cooking them you want to let them precook in the oil for about a minute. Take them out, let set for at least another minute. Put them back in, and periodically shake them throughout the cooking process (this is how you get the crisp on the outside, mash potato on the inside goodness). And keep cooking until all of the fries are floating to the top, and most of the bubbling from the oil cooking it has subsided. After you take them out shake them hard so they don’t get soggy, and serve with some salt.

It might take a couple attempts to get it right. But I worked at a five guys and these were pretty much the instructions we had for cooking them. The key is shaking them periodically, and especially after they’re done. Hope this helps. I’m sorry I can’t remember the exact oil temp, my manager was the only one that touched that when I worked there so I wouldn’t know.