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The Food Lab: Potato Salad Done Right

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Perfect Potato Salad. [Photographs: J. Kenji Lopez-Alt]

Classic Potato Salad

Light, tangy, and flavorful potato salad.
Here's the recipe! »

Potato salad. Big deal, right? It's kinda like background music in a restaurant—something to keep you and your fellow diners distracted and occupied during the awkward silences before the main course arrives. You put an obligatory spoonful on your paper plate and poke at it with a plastic fork until the burgers are done.

At least that's what most potato salad is. The problem is, it's such a simple dish that most of the time, it's made without thought. Boil the potatoes, toss them with some mayo, add a few dollops of whatever condiment catches your fancy, and toss it in a bowl.

But a really well-constructed potato salad can be as interesting as the burger it precedes (and believe me: I love burgers). Tangy, salty, and sweet with a texture that's simultaneously creamy, crunchy, and fluffy in each bite, a perfect potato salad should taste feather-light, despite being made with potato and mayo, two of the heaviest ingredients around.

So why is it that there are so many mediocre potato salads? What could possible go wrong in a recipe that's really got no more than two steps?

Let's take a closer look at some of the hidden complexities, shall we?

The Problems

The way I see it, there are three things that can go wrong with a potato salad. Screw up any one of these, and you're quickly going south:

To find my way to the ideal potato salad, I'd need to address these issues one at a time.

Hot and Cold

First step: getting the texture just right. Potatoes are made up of a series of cells that contain starch granules. These cells are glued together with pectin. As the potato cooks, the pectin slowly breaks down, and the starch granules start absorbing water. When you overcook them, the first thing that happens is the pectin breaks down too far. The potato cells start falling away, and the whole thing turns mushy. Welcome to cold mashed potato city. Overcook them even more, and the starch granules will swell so much that they'll begin to burst, turning a mildly offensive bowl of cold mashed potato salad into an outright disrespectful bowl of gluey, inedible goo.

Undercook them, on the other hand, and your potatoes remain crunchy, and crunchy potatoes are grounds for immediate ejection from the backyard.

It gets even more complex: since potatoes heat up from the exterior towards the center, it's possible to have a potato that's simultaneously overcooked and undercooked. The best way to accomplish this feat of culinary indecency is to drop your cut potatoes into a pot of already-boiling water, like I did to the potato below:

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When the potato starts in hot water, the outside rapidly begins to overcook before the center has even got the chill off of it. Make a salad with these, and you end up with crunchy nuggets of uncooked potato swimming in a sea of gluey mash. No thanks.

Much better was the batch of potatoes I started in cold water. The potatoes heated up evenly right along with the water, so that by the time they were perfectly cooked in the center, the edges had just barely starting to break apart—not a bad thing. I like a little bit of broken up potato to thicken and flavor the dressing.

Of course, even with a cold start, one problem remained: potatoes require constant vigilance—they go from undercooked to overcooked in an instant. Get distracted for just a minute (say, to go chase after your puppy who's just peed on your backpack then hidden your notebook under the couch), and you've got gluey potatoes on your hands.

There had to be a way to solve that problem, but for now, I moved on to the next issue: Seasoning.

'Tis the Season

For some time I've though that it's better to season your potatoes when they are hot, but I'd never actually figured out why. Do they actually absorb more seasoning, or could it just be a psychosomatic effect?

To find out, I cooked three separate batches of potatoes, using green food coloring as a stand in for the salt and vinegar. The first batch I cooked directly in green colored water. The second batch I cooked in plain water, then seasoned with green-colored water after draining while they were still hot. The last batch I allowed to cool completely before adding the green water.

After all batches were completely cooled, I cut a cube of each in half to see how far the food coloring had penetrated.

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You can see from the results that it clearly makes a big difference to season when hot. The potatoes cooked in seasoned water and seasoned while still hot appeared a light shade of green all the way to their centers, while the potato that was seasoned after cooling was mostly pale in the center, with a single green streak where a natural fault in the potato occured.

The reason for this is twofold. First, the cooked starch on the surface of the potato hardens and gelatinizes as it cools, making it harder for anything to penetrate. Secondly, as the potato cools, it contracts and tightens up slightly, making it harder for any seasoning to work its way into the center even if it manages to make it past the gelatinized starch sheath on the exterior.

Look carefully at the time lapse photos below, and you can see that the potato on the right, which was taken a full 30 minutes after the potatoes were drained, is ever so slightly smaller than the potato on the photo at the left (look at the left arrowhead, and notice how it extends beyond the edge of the potato in the photo at right).

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The difference may look small to the naked eye, but to a molecule of vinegar trying to work its way into a spud, that makes all the difference in the world.

You may have noticed, like I did, that whether or not the potato was cooked in seasoned water or seasoned immediately after coming out of plain water, it made very little difference in terms of flavor penetration. Might as well just add the vinegar to the potatoes after they're cooked, right? But there's a very good reason to add a little vinegar to the potato's cooking water: it prevents it from overcooking, something I learned a while back when I was on my quest for French Fry perfection. Pectin breaks down much more slowly in acidic environments. A tablespoon of vinegar per quart of water was enough to allow me to boil my potatoes without having to worry about whether or not they'll overcook while I'm distracted by the dog.

Overcooking problem solved.

This Spud's for You!

At this point, I asked myself a basic question: are russets really the right potato for the job?

Potatoes vary widely in their texture. Russets, with their grainy, fluffy texture are at one extreme, while red potatoes, with their waxy, creamy interiors are at the other. Yukon golds, the other commonly available variety, bring up the center.

I knew that waxy potatoes would yield a slightly firmer texture in the finished salad, but that's not necessarily a good thing. More importantly, how would they take to seasoning?

I repeated my green potato test, this time with red potatoes versus standard russets.

The results were clear:

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A russet potato, with its granular, open texture, is far better at absorbing seasoning than its dense, waxy, red counterpart. Russets for the win.

Balancing Act

Now that the potatoes were perfectly cooked, light, and bright, the rest was simple: balancing flavors. Nothing too hardcore nerdy here. Rice wine vinegar is my favorite all-purpose vinegar, and it works well. Two tablespoons in the cooking water, another to dress the hot potatoes, and a final two in the mayonnaise mixture added plenty of layered brightness. Mayonnaise—be it storebought or homemade—is a must. A cup and and a quarter is less than average for 4 pounds of potatoes, but I like to keep the mayo a little light. By stirring the salad vigorously, you can bash off the corners of the potatoes, which get mashed up and extend the amount of creamy dressing to tender potato chunks. For heat I added a few tablespoons of whole grain mustard.

Pickles are a point of contention in potato salad. I like to use chopped cornichons in mine, mostly because that's the type of pickle I most commonly have in my fridge. Chopped dills, bread and butters, or even a couple scoops of pickle relish workjust fine. Chopped celery and red onions add necessary crunch to the mix.

I once got into a fight with a fellow cook (that ended with a ripe avocado smashed against the wall) over whether or not sugar should go in potato salad. He's now the Chef de Cuisine at the venerable Manresa in Los Gatos, while I'm just a humble blogger. You decide who's right

For the record, I like still the sugar. But to be honest, once the potatoes are properly cooked and seasoned, the dressing itself is very much a matter of personal taste. Whether or not it needs black pepper is not. Put the pepper in there.

There're few dishes much humbler than potato salad, but if you want to gussy it up a bit, you could do worse than to add a handful of fresh chopped herbs. Parsley and chives work great. I used scallion greens because I had tons leftover from this week's wokfest. If you've saved your celery leaves, you can go ultra-fancy by using them as garnish.

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Now I know that there are those who like to use pickle juice. Those who like to add garlic. Those who add sour cream. Really, all those things could be great, and as far as flavorings go, there's no right way to make a potato salad. The keys are to remember:

I just realized I used up 2,000 words to explain four sentences, and half of them were about dying potatoes green. What has my life come to? My sincerest and deepest apologies. Would that you may find a more productive way to procrastinate on friday mornings in the future.

Happy 4th!
Continue here for Classic Potato Salad »

About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.

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