Why It Works
- A low-temperature "blanch" in salted water solidifies the pectin and partially gelatinizes the starch in the potato, yielding crispy, blonde, perfectly seasoned fries.
- Frying the potatoes twice allows the starch on the exterior to retrograde, producing fries that stay crispy once out of the fryer.
You're going to need a lot of paper towels.
That's the first thing you need to know about making shoestring fries at home. Not just one square, or two, but many, many more; depending on how many batches of fries you plan on making, you might need a whole roll, since the process of turning spuds into threads of potato that fry up crispy on the outside and yet retain more than a wan suggestion of fluffiness within requires blotting: blotting of water, blotting of oil, blotting of oil (again), each bit of blotting requiring a fresh sheaf or two of paper towel product in order to ensure that what you have blotted does not unblot itself and adhere to the potato threads again.
Yes, it's a lot of paper towels.
(You can, of course, use clean, cotton, lint-free kitchen towels, but I did not. In the blot war between paper and cloth, the convenience of tossing all that paper forced the hypothetical cleaning of cloth into a rout.)
Why emphasize this blotting, this waste of paper? Well, frying up French fries at home is a pain, because it's almost necessarily a batched process—that "almost" is there only to acknowledge that there must be someone, somewhere out there who has commercial deep fryer in their home kitchen. But the rest of us don't, which means if we want to make enough fries to barely satisfy four people, we'll need to fry them (twice) as quickly and efficiently as we can, using a pot with about two quarts of oil, which means cooking them in batches so the oil temperature remains high enough to crisp them up and cook them through without getting greasy.
And, as with any extensive, batched deep-frying process involving ingredients that contain relatively large proportions of water, the fine odor of fry oil will perfume your house, in part because every exposed surface in your kitchen and any adjacent rooms will be misted with oil. You will have to clean not just pots, not just utensils, but your counters, your walls, your ceiling, too, if you can manage it. Are you sure you're up for this? Really? You don't want to just go to literally any restaurant or takeout spot, order some fries—they may not be great, but they're still gonna be fries—and call it a day? No?
Okay. I get it. You want to fry fries at home, but not just any fries: You want great fries, so good that, were you served them at a restaurant, you'd order more. That's great, because we already have you covered! Kenji López-Alt's recipe makes some of the greatest fries you'll ever eat, at home or anywhere else. "But wait," someone calls from the back of the room, "I like really thin fries!" That person—you, maybe—doesn't want just fries, they want fries the the thinness approximately of a julienne, or a thick matchstick, like the kind you use to light a fireplace fire; they want those potato pieces as close as possible to the dividing line between fries (amazing, the platonic ideal of potato preparation) and potato "stix" (perfectly fine, really, but just buy them in a bag at the bodega). They want what people call "shoestring" fries. Okay, we can do that, too.
Before we go any further, I must confess to some confusion about nomenclature. What is a shoestring fry? I asked around, and no one could agree. "Matchsticks," said one person; "julienned fried potatoes," said another; "like potato 'stix'," said a third. Arguably, these all could mean the same thing, but taken literally, they are not the same.
If you search online, a brief scan of images results shows some frankly burnt-looking sticks of potato mixed among pictures of...French fries. None of them look much like shoe strings, to my eye. Thus, I realized that I had to take to heart that absurd injunction made popular in recent years in the political sphere: I had to take the phrase "shoestring fries" seriously, not literally, which means I could project whatever qualities I want onto it. And so, my definition of shoestring fries is this: good French fries, just thinner, thin enough to distinguish them from normal good French fries. Other than thickness, the qualities should be identical to a good French fry: fried to a nice potatoey blonde, fluffy insides, well-seasoned (in and out), crispy on the outside, magically able to stay crispy for longer than an hour.
Now if you disagree, I'm sorry. If you like your shoestrings to be potato sticks that shatter into a million arid bits in your mouth and become irretrievably stuck in your molars, then this recipe, as written, will not satisfy you. If you like your shoestrings brown, not attractively golden, then this recipe is your enemy. However, I will offer some suggestions below for how to tweak this method, which in itself is a tweak of Kenji's French fry method, to produce those results.
What Is a Shoestring's Thickness?
Since there isn't a consensus out there about the thickness of a shoestring fry, I started by cutting russet potatoes into a variety of fry-like thicknesses using a mandoline slicer and a sharp knife. Regardless of the kind of fry you're making, you will probably want to use a mandoline slicer, since they're quite convenient and produce consistently sized slabs (or twigs) of potato; for shoestrings, you will definitely want a mandoline, unless you are a professional cook with a prep cook's knife skills, who, in any case, would tell you to use a mandoline. So in addition to reams of paper towels, be sure to have a mandoline on hand. And, if you're using a mandoline, you should absolutely pick up a cut-proof glove (or two) so that you can use the mandoline without risking a trip to the emergency room.
I didn't really have a method, I just made a bunch of French fry cuts with different dimensions (I used a pair of digital calipers to figure out those dimensions after the fact), and then I fried them all according to Kenji's French fry technique, altering it on the fly depending on the dimensions in question—thinner fries got shorter blanches and fry times, etc. I ended up settling on ~3mm by ~3mm (1/8" x 1/8") as being thin enough to be distinguishable from a good fry, but not so thin as to make it impossible to produce anything but potato "stix."
Adapting French Fry Technique for Shoestrings
Cooking these ~3 mm by ~3 mm potato matchsticks according to the French fry recipe left a little to be desired. Even with sensible modifications, the shoestrings I was making were both a little too dark and had interiors that were too blown out; there wasn't much of that pillowy softness that you like in a proper French fry, although they were plenty crispy. In fact, they stayed crispy for hours. I guess I could've just made potato "stix" and called it a day, since a lot of people apparently think potato "stix" are shoestrings, and we could have all just gone to war in the comment section. But my entire apartment already smelled like potato and fry oil, so I kept going.
The main issue seemed to me to be that the fries were overcooking—too dark, blown out—but I didn't have the best luck with shortening the fry times, since that just left me with limp fries. I started getting very fiddly with the initial blanch, but then, while rereading Kenji's account of his previous experiments, I latched onto the idea he tried (and then subsequently dismissed as being...too fiddly) involving a low temperature "blanch." Kenji notes that McDonald's is said to use this step, and...well here's what he says:
Pre-cooking the fries in a water bath the way McDonald's does accomplishes two goals. First, it rinses off excess simple sugars, helping the fries attain a light gold color, instead of a deep dark brown. Secondly, it activates an enzyme called pectin methylesterase (PME). According to an article in the Journal of Agricultural and Food Chemistry, PME induces calcium and magnesium to act as a sort of buttress for pectin. They strengthen the pectin's hold on the potato cell's walls, which helps the potatoes stay firmer and more intact when cooked to a higher temperature.
(Note that calcium and magnesium strengthening pectin is one of the reasons beans can become very hard to cook, as explained by Nik Sharma in his bean-brining investigation.)
Kenji ultimately abandons the low-temp "blanch" in favor of using vinegared water to strengthen pectin in his fries. But as I went about blanching very thin French fries, I found the big vat of boiling water, the temperature of which would drop far below boiling once a mass of thin fries was added in, to not be very convenient. The precipitous drop in temperature also made timing of the blanch a little subjective, and therefore tricky, and I found that, more often than not, my shoestrings were getting overcooked at this initial stage, even when blanched for just under two minutes (as opposed to the 10 minutes called for for French fries.)
Instead, I started using the low-temperature "blanch": I'd bring four liters of water, seasoned with salt and vinegar (more on that in a second) up to about 170°F over high heat, dump in the thinly cut potatoes, then monitor the temperature until it went back up to about 165°F, which takes just a minute or so. Then I would turn off the heat, cover the pot, and let it sit for about 15 minutes, after which I'd drain the potatoes and put them on (yup, it begins) a bunch of paper towel-lined baking sheets. The result was almost "cooked" potato threads (they're still a tad crunchy) that are perfectly seasoned and very well set up, from a pectin perspective. In addition to being less subjective (if you use the called-for quantity of water and you have and use an instant-read thermometer), it's also a little more relaxed; you can take those 13 extra minutes of doing absolutely nothing to either clean up or start lining baking sheets with paper towels.
But wait, why the vinegar? Well, I kept using it as a hedge against the possibility that I might look away as the potatoes and water are heating together; if the water went over 170°F, it might spell disaster for the enzymatic reaction, but it needn't spell disaster for the fries. After many trials, I've found it is very easy to not exceed 170°F, so the vinegar isn't altogether necessary, unless you would like to live dangerously and go with a blanch with boiling water. However, even with the low-temp "blanch," I include the vinegar because, as a placebo, it is very effective at relieving my anxiety about making bad fries, and it doesn't impart any flavor at all, so why not?
From there, it's very straightforward: you double-fry the parcooked potatoes, first to drive off water, then to crisp them up. There are two things to keep in mind for frying, the first has to do with kitchen safety, the second with crispiness: Do not try to rush through the process by adding more cut, blanched potatoes to the hot oil than indicated, and do wait until the oil-blanched fries have fully cooled down before giving them the second fry. The first point is for your safety: the low-temp "blanched" fries are very wet, even after sitting on a mound of paper towel product, and wet stuff added to hot oil will froth and sputter and... if your oil boils over the edge of your frying vessel, you may start a fire. If you don't wait until the fries cool down at least to room temperature-ish, the starches on the exterior of the fries will not retrograde fully, which means when you fry the fries for a second time, they will not get as crispy. The whole point of the "blanch" and the double-fry—the whole point of this entire process!—is to produce crispy fries, so don't forget that last bit.
Of course, given that the fries have to be done in batches anyway, both for maximum crispiness and maximum safety, if you make the recipe as written, there will be ample time for the first batch of oil-blanched fries to cool down before the last batch is blanched the first time in oil. But if you make less? Just don't cook the fries a second time until they've cooled down (also, don't make less; if anything, you'll want to make more). If you're worried that your already fried fries will go limp and soggy while you're doing the second fry on the remaining batches, relax: These fries will stay crispy for a long time.
However, they will not stay hot. If you want to serve your fries hot, you will need to serve them right out of the fryer. You can compromise on fry hotness by waiting until all the fries are ready to go, which will leave you with some hot, some warm, and some lukewarm, and yet all of them still crispy. Alternatively, you can stash the fried and seasoned fries in a low oven on a baking sheet, but depending on how long it takes for you to complete the entire process, you run the risk of drying them out. My suggestion is to just serve them immediately as they come out of the fryer.
The result is perfectly blonde, perfectly crispy, perfectly fluffy-on-as-much-as-a-matchstick-has-insides, perfectly seasoned fries. This last bit I mean; these fries, straight out of the fryer, barely need a sprinkling of salt. In fact, after eating many, many, many shoestring fries, I found I preferred them sprinkled with chaat masala (which has just a bit of salt in it). They are frighteningly good that way.
"Wait! I Want Bad Shoestring Fries!"
Ah, almost forgot. Some of you would like your shoestrings to be crunchy, not crispy; some of you would like your fries brown. Well, the funny thing about starches and their gelatinization is that all you have to do is alter the blanching step to get the results you crave; everything else, including the fry times, stays the same.
For browner, crunchier shoestrings, 50% of which have blown out insides (thus making them even crunchier), all you have to do is blanch the potato matchsticks in vinegared, salted, boiling water for just under two minutes, then drain them on an excess of paper towel products. The explanation for it is, I think, that the higher temp fully gelatinizes the starches on the exterior, which leads to more efficient browning and crisping. However, if you do this, you will want to watch the potato threads during the initial water blanch like a hawk; overcooking them slightly will lead to many broken pieces. Better to err on the side of undercooking than overcooking.
- 2 pounds russet potatoes (900g; about 4 large potatoes), peeled and cut into 1/8-inch by 1/8-inch (3mm x 3mm) matchsticks and submerged in cold water
- 4 quarts (3.8L) water
- 1/4 cup (36g) Diamond Crystal kosher salt, plus extra as needed; for table salt use half as much by volume or the same weight
- 1/4 cup (60ml) distilled white vinegar
- 2 quarts (1.9L) neutral oil, such as peanut or vegetable, for frying
Line a rimmed baking sheet with a double layer of paper towels. In a large, tall-sided pot, combine water, salt, and vinegar and bring to 170°F (76°C) over high heat. Drain potatoes, add them to pot, stir, and let water come back up to around 165°F (74°C) (try not to exceed 170°), about 1 minute. Cover pot, turn off heat, and let potatoes sit for 15 minutes. Using spider strainer, transfer potatoes to prepared baking sheet and let cool, about 15 minutes; discard water.
Set a wire rack in a second rimmed baking sheet, and line with paper towels. In a large Dutch oven or carbon steel wok, bring oil to 400°F (200°C) over high heat. Reduce heat to medium-high and carefully add 1/8 of potatoes to hot oil (oil temperature should drop to about 360°F) and cook until vigorous bubbling subsides and potatoes just begin to color, about 30 seconds. Using spider strainer, transfer potatoes to prepared baking sheet, and let cool at least 30 minutes before proceeding to second fry.
Repeat step 2 process with remaining potatoes.
Line a large bowl with paper towels. Bring oil back up to 400°F over high heat. Add 1/4 of cooled, oil-blanched potatoes to oil and cook just until potatoes are crisp and just slightly blonder than you'd like, about 40 seconds. Transfer fries to prepared bowl, taste, and season with more salt or seasoning mix, to taste. Repeat with remaining potatoes. Serve immediately.
Large Dutch oven or carbon steel wok; spider strainer; baking sheets; wire rack; a lot of paper towels.
For safety reasons, this recipe calls for adding a relatively small amount of shoestrings in each fry step. However, if, after fry-blanching the first batch of shoestring fries, it seems to you that you can safely add more shoestrings to the hot oil without causing an overflow, by all means do so, but do it carefully, by which I mean incrementally.
For darker, crunchier shoestring fries, bring the salted, vinegared blanching water in step 1 to a rolling boil, add the potatoes, bring the water back up to a boil, cook for about 1 minute and 30 seconds, and then drain. You can then proceed with the recipe as written.
Make-Ahead and Storage
Once fried for the second time, shoestring fries are best served and enjoyed immediately. If you want to prep in advance and break up the cooking process, you can follow the recipe through step 3, cover and refrigerate (or freeze) the cooled oil-blanched potatoes, and complete the second fry at a later time. This approach is convenient for professional kitchens outfitted with deep fryers, but is more of a hassle for home cooks who have to make room on their stovetop or somewhere in their kitchen for a pot of oil between rounds of frying.