Thoroughly scrub and clean potatoes if cooking with skin. Then use a paring knife to clean and remove any spoiled spots, such as bruising and discoloration.
If you choose to peel them, place the peeled potatoes in a bowl of cold water, so they don't turn dark while you peel the rest. Make sure the potatoes are completely submerged in the water.
Using a sharp knife, cut potatoes in 4-5 vertical slices, then cut each slice into sticks, depending on your preference. Remember, the thinner the fries, the crispier they get.
Place cut potatoes in the bowl of water - the potatoes should be fully submerged in water. Then allow them to soak for two or three hours. (Note: Alternatively, you can put them in the fridge and soak for several hours or overnight to remove excess starch. It helps make to make the fries crispier.)
When ready to fry, line a cookie sheet or large plate with paper towels. You might have to use more than one plate or cookie sheet. Set aside.
Drain off the water and lay them on a prepared cookie sheet. Pat damp fries with paper towels to dry out. If possible, let it air dry for about 10 minutes before frying.
Heat the oil in a deep fryer or cast-iron skillet to 300℉/160℃.
Carefully drop the fries in hot oil for about 5-6 minutes. Potatoes should be soft and tender but not brown.
Using a large strainer spoon to remove potatoes fries, gently shake off the excess oil, and let them drain on a plate or rack. Continue frying the remaining potatoes until you have par-cooked all the potato fries.
Crank up the heat to 350℉/177℃.
Return potatoes back to the fryer in small batches, frying until they're golden brown and crispy, about 2-3 minutes.
Remove from oil, then shake off the excess oil and immediately toss with seasoning.
Repeat until all potatoes are cooked.