Anyone who saves their leftover french fries with the intention of reheating and eating them later is a true optimist, and deserves to be rewarded. And what better reward than an explainer on how to reheat your french fries so they turn out hot and crispy?
But first: DON'T reheat your french fries in the microwave. They'll just turn out soggy. But you probably knew that, which is why you googled instead of just nuking them to begin with.
How to Reheat Fries
Now, since not everyone has access to the same equipment, not every technique here will work for everyone. And depending on what quantity of fries you're looking to reheat, some methods might not be worth the trouble.
So we'll start with the best all-around method before discussing some alternate techniques that also work well. Note that for all the methods described here, you're going to want to make sure you start out with fries that are at room temperature. So if you have them in the fridge, take them out 30 to 60 minutes before you begin.
Use a Convection Oven (or Air Fryer)
If you have a countertop convection oven, or an oven with a convection setting, or even an air-fryer, you're in luck. Because short of deep-frying, a convection-style cooking device is the best way to reheat leftover french fries.
The way convection ovens work is that they feature a powerful fan that blows hot air around the oven. This not only accelerates cooking times but it also is extremely effective at making foods crispy. That's because instead of just sitting in a hot oven, the food is being blasted with hot, dry air. So the exterior of the food gets extra brown and crispy, while the interior heats in the usual way.
And with french fries, it's really all about heating the exterior. This is why the microwave doesn't work. The microwave cooks from the inside out, heating the moisture inside the french fry, producing moist, steamy air, rather than hot, dry air. Hence the soggy fries.
A convection oven or a regular oven with a convection oven are your best choices, since they let you spread out your fries in a single layer. Set your oven to around 400 F, with the convection fan on, and heat for 5 to 10 minutes or until hot and crispy. You might need to flip the fries once during heating.
An air-fryer, which is much smaller, forces you to work in batches, and you'll need to shake the basket a few times during cooking. Even so, an air-fryer will still do a very good job of reheating french fries.
Reheat Them in the Oven
The next best method, if you don't have any convection-style equipment, is to reheat your fries in the oven. Get your oven nice and hot, like 450 F. Now, and arrange your fries on a flat sheet pan in a single layer and give them a light spritz of cooking spray. Heat for 5 to 10 minutes, flipping once during heating.
Reheat Them in a Skillet
This technique will work well for smaller amounts of fries, although it's the one method that won't work as well for tater tots or curly fries. If you're reheating items like those, any of the other methods described here will probably work better.
Start by heating about two teaspoons of vegetable oil in a wide skillet over medium-high heat. A cast-iron skillet is really good for this. Once the oil is shimmering, add your fries in a single layer, being careful not to crowd the pan. Let the fries heat while turning regularly but not incessantly. You want a chance for the fries to heat through while allowing the hot oil to crisp up the exterior.
Saute in this manner for 3 to 5 minutes, depending on how thick your fries are, then serve. A fresh sprinkling of salt at this point is certainly not a bad idea.
In the final method we'll discuss, you'll return your leftover fries to the hot oil from whence they came. This has the advantage of simply repeating the cooking method that originally made your fries so delicious in the first place. Of course, it's also the most time consuming and least practical. But if you happen to have a deep fryer with the oil already in it, you might want to seriously consider it.
Simply heat your oil to 325 F and fry your fries for 1 to 2 minutes, then drain, reseason and serve.