Scrub the potatoes and peel if desired (I leave the peels on). Slice in half lengthwise, then cut into 1/4-inch-wide slices (a mandoline is the best way to get even fries; watch your fingers!). Turn the slices on their sides and cut into 1/4-inch sticks. If the sticks are long, cut them in half so that your fries are about 3 to 4 inches.
Place the potatoes in a large bowl, then pour very hot tap water over the top so that it covers the potatoes by at least 1 inch. Let sit 10 minutes. <—Must do! If you skip the soaking step, the fries will not be as crisp.
If you’d like to keep the fries warm between batches, preheat the oven to 200 degrees F and keep a baking sheet handy.
Preheat the air fryer to 375 degrees F according to the manufacturer's instructions. (For my air fryer, that is 3 minutes of preheat time).
Drain the potatoes, then transfer them to a clean towel and dry as completely as you can, changing the towel as needed. Rinse and wipe out the bowl you soaked the potatoes in, then return the potatoes to the bowl.
Drizzle the potatoes with the olive oil and sprinkle with salt, garlic powder, black pepper, and any other desired seasonings. Toss to coat, making sure the spices and oil are well distributed.
FOR FAIRLY CRISPY, SATISFYING FRIES IN FEWER BATCHES: Place the potatoes in the air fryer basket, doing no more than two layers (my air fryer is 5 1/2 quarts and I can add about 1/3 of the fries). Make sure the fries are not completely packed together so that the air has plenty of room to circulate. Cook the fries for 5 minutes. Slide the basket out and use tongs to toss the fries. Return to the air fryer and continue cooking for 3 to 7 additional minutes, until crispy and golden brown. The time can vary by several minutes based on your air fryer model. Check on them a few times during the last few minutes to make sure they don’t burn and make note of the time for future batches.
FOR MAXIMUM CRISPY FRIES IN MORE BATCHES: Place the potatoes in just one layer in the basket, being careful that they don't touch much or overlap. Cook for 4 minutes, slide the basket out and flip with tongs, then continue cooking for 4 to 8 additional minutes, until the fries are as crispy as you would like (again, the time will vary based on your model, so check them several times during the last few minutes and adjust as needed).
Remove the fries to a baking sheet or serving plate and immediately sprinkle with kosher salt.
Repeat with remaining potatoes, keeping the cooked fries warm on a baking sheet in the oven between batches as desired. Discard any liquid the potatoes have given off that has collected at the bottom of the bowl. Sprinkle with any extra desired toppings. Enjoy!
*Russet potatoes are drier inside and give you a fry more similar to what you’d have in a restaurant. Yukon golds will give you fries with firmer, creamy insides and crispy outsides. We love both! Feel free to use your favorite or try them both ways.
**You also can make air fryer fries with no oil. Coat the air fryer rack with non-stick spray to prevent sticking.
TO STORE: Place leftover fries in an airtight storage container in the refrigerator for up to 3 days.
TO REHEAT: In the unlikely event of leftovers, you can reheat the baked fries in the air fryer at 375 degrees F or by preheating your oven to 400 degrees F and placing an empty baking sheet in the oven while the oven preheats. Spread the leftover fries in a single layer on the hot pan (or in the air fryer basket), and recrisp. Nothing replaces the just-cooked taste (the fries will dry out a bit), but they do perk up. I found air fryer fries reheated even better than regular fries, since the lesser amount of oil inherently prevents them from getting soggy.