Crispy, delicate crusts
Evenly tender interiors
Rich French fry flavor
Peel, cut, fry, let cool, fry again, drain. Repeat with remaining batches. Let oil cool and, finally, discard oil. I think I speak for French fry lovers everywhere when I say that the tawny, crispy crusts and velvety interiors you get from a proper fry job are worth all the grease—elbow and otherwise. But given what the process entails, I make real fries about as often as I make croissants or pasta from scratch, which is to say almost never.
Most people's alternative to deep-fried fries is oven fries, which are usually less fussy to make, often less greasy, and always a disappointment. OK, that might be a bit harsh, but I think you'll agree that oven fries frequently fall short. The most basic methods call for simply tossing cut potatoes with a few tablespoons of oil, spreading them in a single layer on a rimmed baking sheet, and roasting them in a hot oven for about 30 minutes, turning them a few times so that all sides make contact with the hot surface and brown. More-involved recipes take the time to parcook (usually either by boiling or microwaving) the cut potatoes before the oven phase, which helps the insides turn tender by the time the outsides are brown.
The perks are obvious: No lengthy potato prep work, no grease-splattered stovetop to clean, no vat of hot oil to deal with afterward. But in my experience, oven-fried potatoes rarely cook up with a French fry's evenly golden exterior, instead emerging pale or flabby in spots or shriveled and tough at the edges. Worse still, they lack that unmistakably lush, nutty, subtly savory “fry” flavor of French fries. What do they taste like? Compromise and wasted potential.
But what if you could have it both ways: the flavor and crispiness of deep-fried fries produced with no more work than roasting potatoes? For the sake of French fry lovers everywhere, I had to try.
To understand what goes wrong when you “fry” in the oven, I took a closer look at the aforementioned basic method. I cut 2 pounds of peeled russet potatoes into ½-inch-thick planks; tossed them with 4 tablespoons of vegetable oil, a common amount used in other oven fry recipes; spread them on a heavy-duty rimmed baking sheet that wouldn't warp in the hot oven; and cooked them at 425 degrees for about 30 minutes. (If the oven were any hotter, the oil would smoke and give the fries an acrid flavor.) I flipped the planks a few times during cooking so that they could brown all over.
There were two problems. First, the potatoes weren't tender by the time their exteriors were brown, which explained why some oven fry recipes called for parcooking the potatoes. Second, while each side of the potatoes was at least somewhat brown, only the sides originally in contact with the hot baking sheet were actually crispy; the other surfaces were tough and leathery.
Those flaws made sense when I considered how fried fries are typically made. Most recipes call for frying the potatoes twice. The first fry, often called blanching, cooks the potatoes through and causes the surface starch to gel. You then remove the potatoes and let them cool briefly before frying them again, which rapidly drives the water out of the starch gel at the surface, leaving behind tiny cavities. It's these cavities that lighten the crust during the second fry so that it shatters when you bite through it.
The problem with my oven fries was that the water in the potatoes wasn't heating rapidly. It was heating slowly, because air doesn't conduct heat as quickly as oil does. Consequently, no air pockets are formed and the starch molecules nestle together, leading to a tough crust.
Proof's in the Pudding
To ensure tender fries, parcooking the potatoes was definitely in order. I could blanch them in water, but it would be more efficient to cover the baking sheet tightly with foil for the first part of cooking so that they could steam. After a few trial rounds, I determined that about 12 minutes under cover parcooked the potatoes enough that they would be fully tender by the end of the uncovered phase.
As for creating a crispy exterior, what if I could put a different starchy coating on the outside instead of relying on hot, bubbling oil to crisp the potato starch? Cornstarch is what I had in mind: Like those of potato starch, its particles are quite small, which is why we've had good luck in the past using it as a fry coating on everything from chicken wings to sweet potato wedges. Plus, its starch granules—much finer than those of potatoes—don't hold on to much water and don't hold on to it tightly, so it can easily form a crispy crust. Plus, it's an ingredient that most cooks keep on hand. But instead of simply dusting cornstarch directly on the food, which we've found can leave a chalky film in your mouth, we prefer to mix the cornstarch with water to make a slurry. Doing so hydrates the starch, essentially creating a batter that coats the food.
I spent the next several tests mixing up different ratios of cornstarch and water, but no matter what I tried, I couldn't produce a batter that coated the potatoes evenly. Thinner slurries slid right off the potatoes and pooled on the sheet, while thicker batches formed goopy clumps. What I wanted was that loose, pudding-like consistency you get when cooking cornstarch in a warm liquid, as you would when thickening a sauce. So for the next test I microwaved the slurry (3 tablespoons of cornstarch mixed with ¾ cup of water) for a minute or so, giving it a stir periodically. That helped; the cornstarch absorbed the water and thickened into a smooth pudding that coated the potatoes beautifully. I had, in effect, re-created the starch gel found on the surface of traditional oil-blanched fries.
I arranged the slurry-covered spuds on the oiled baking sheet, covered the sheet tightly with greased aluminum foil (to prevent it from sticking), and cooked the potatoes for 12 minutes before pulling off the cover and letting the potatoes brown for about 10 more minutes. I then flipped the fries and let them brown for another 10 minutes. The results were better than any I'd had to date: On most pieces, the coating was crispy and delicate and gave way to a fluffy, evenly tender interior. The problem was that the oil was pooling on the baking sheet, leaving some of the fries saturated and a tad greasy and others almost dry, meaning that they stuck to the sheet and didn't crisp. And they still didn't deliver that rich “fry” flavor.
How Low Can You Go?
One quick change I made was to swap the russet potatoes for Yukon Gold potatoes, since the latter have a naturally buttery flavor that hinted at the richness of real fries. Their skins are also thinner than those of russets, so they didn't require peeling.
Oil pooling on the cooking surface is a problem we've run into before, most notably when we developed a recipe for Thick-Crust Sicilian-Style Pizza (March/April 2015). Our solution there was to spray the baking sheet with vegetable oil spray before coating it with oil. Odd as that sounds—grease held in place with grease—the cooking spray contains a key ingredient that oil doesn't: lecithin, a surfactant (an ingredient that reduces tension between a surface and a liquid) that helps the oil flow to coat the metal evenly and form a thin, complete layer between the baking sheet and the food.
I made another batch of fries, this time spraying the sheet before adding the 4 tablespoons of oil, and the results were much better. No more sticking, and the fries were evenly golden on the two flat sides. But now that the sticking wasn't a problem, did I even need 4 tablespoons of oil? After all, relative leanness is another supposed selling point of oven fries. Maybe I could get away with less, and that would help the greasiness, too.
I made several more batches, coating the potatoes with varying amounts of fat, including an ambitious batch where I used only the spray. I was able to take the oil down to 3 tablespoons and the fries still cooked up crispy; even better, the greasiness was gone and they delivered that rich, savory, from-the-fry-o-lator flavor (for more information, see “What Puts the ‘Fry’ in These Potatoes?”).
These spuds cooked in the oven truly deserved the title of “fries.” They were delicately crispy on the outside, fluffy within, and full of fry flavor. In other words, they tasted like victory.
What Puts the “Fry” in These Potatoes?
Keys to Success
Crispy, delicate crustsCoating the potatoes in a cooked cornstarch slurry creates a thin starchy shell that mimics the crust of a deep-fried fry.
Evenly tender interiorsCovering the baking sheet with foil for the first part of the cooking time steams the potatoes so that they’re evenly tender by the time they brown.
Rich French fry flavorThree tablespoons of oil breaks down just enough in the hot oven, creating new flavor compounds that imbue our fries with the distinct flavor of potatoes that have been deep-fried.
No stickingCoating the baking sheet with cooking spray (which contains a surfactant called lecithin) before adding a coat of oil prevents the oil from pooling and, thus, prevents sticking.
Well-browned exteriorsSquaring off the tapered ends of the wedges creates even rectangles with flat sides that brown nicely.