If making fry sauce, combine all ingredients and set aside. 

Carefully cut potatoes vertically into 1/4″ slices.

Divide stack in half with the flat surface of the potato on the cutting board and carefully cut potatoes into 1/4″ fries (you may need to remove the round top slice and then cut that part later if you find it’s slipping while you’re trying to cut the potatoes).

Toss any pieces that are too skinny–they’ll just burn when you’re cooking–and trim down any extra-large pieces. Place cut potatoes into the bowl of ice water and repeat with remaining potatoes. When finished, pour the entire bottle of oil into the pot/kettle/deep fryer and bring to 325 (keep the candy thermometer in there the whole time) over medium-high heat. When the oil is about 310-315 degrees, drain the potatoes so they’ll be ready to go into the oil as soon as it’s hot enough.

First fry: When oil reaches 325, turn the heat all the way up to “high.” Place 1/2 of the potatoes into the hot oil and stir frequently for 5-6 minutes, or just until they’re starting to show signs of being cooked. Remove from the hot oil and drain on one of the paper towel-lined plates. They look a little grim. Fear not! We’re not done yet.

Bring the oil back to 325 and then fry the second batch of potatoes. You know the drill–stir frequently, remove after 5-6 minutes, drain on paper towels.

Now…this is where things get fun. Bring the oil up to 375. When you’re there, add the first batch of fries back to the oil and fry for 1-2 minutes. They’ll get brown and crispy fast, and they’ll continue to brown a little after you remove them from the oil, so as soon as they start getting brown enough, get them out of the oil and drain them on the paper towels. As soon as they’re out, give them a very liberal sprinkling of salt while they’re still very, very hot.

Bring the oil back to 375 and fry the second batch of fries, following the same directions. Serve immediately with fry sauce.