Fill a large bowl with cold water. Place potatoes in water as you peel them to keep them from turning dark. One by one, cut peeled potatoes in half, lengthwise. Place each half flat-side down and slice into 1/2-inch thick pieces. Stack these slices, one on top of the other, and cut potatoes again lengthwise into 1/2-inch pieces.
You should now have rectangular fries that are 1/2 inch on each side and as long as the potato. Soak potatoes in water for five minutes to release some of the starch and to keep potatoes from darkening.
Drain potatoes in a colander and blot dry with a clean cloth dishtowel. Avoid paper towels because they will stick to the potatoes.
All cooking equipment and food to be fried should be bone dry. Moisture will cause oil to splatter.
Pour 2 quarts of oil or enough to completely immerse potatoes into a heavy, tall-sided pot or Dutch oven.
Clip your deep-fat frying thermometer to the side of the pot so the tip of the thermometer is in the oil but not touching the bottom. Once the oil has reached 320 degrees (If you have no thermometer, test one fry. It should float, the oil should bubble, and the fry should begin to brown.) Stand back. The oil will spatter and bubble.
Using a fry basket or mesh skimmer, gently lower fries into the oil one small batch at a time. Fry potatoes 2-5 minutes, or until you can crush one easily.
Use tongs to remove one fry from the oil and a spoon or other utensil for the crush test. The fry will be very hot.
When ready, remove fries from the oil and set on a baking sheet lined with paper towels to drain.
Just before serving, fry potatoes a second time. Begin by heating oil up to 360 degrees. Fry until medium golden brown (about 3 to 5 minutes), drain, salt, and serve with the condiment of your choice.