"Kenji, why don't you ever make those salt-crusted potatoes we have back home for me?" my wife, Adri, said to me the other day as we were driving home from an afternoon at the beach. As the husband of a Colombian woman, I've come to learn a couple things about their culture. Namely, when it comes to dancing or potatoes, you'd best open up your ears and listen, because they don't mess around in either department.
I knew exactly what potatoes she was talking about. The first time I encountered them was a few years ago when her uncle innocently invited us to lunch at his apartment in Bogotá. Before we arrived, Adri warned me in no uncertain terms to take the smallest possible portion the first time around, because my plate would be refilled at least four more times whether I wanted it or not. It all started well as I loading my plate with the thinnest, most delicate slice of sobrebarriga—flank steak roasted until fall-apart tender—and a small spoonful of beans, but it started heading south when I got to the potatoes, for in front of me was this:
Tiny new potatoes bursting with buttery flavor under a crisp, salty, crystallized crust. Their appearance was mesmerizing and their flavor intoxicating. I'm a salt fiend (and you've gotta be to enjoy a dish like this), but I'd never tasted anything quite like this before. Served with ají, a Colombian-style fresh salsa, I couldn't help myself. Before I knew it, I'd filled up on them.
Big mistake. By the time I left that apartment, I'd been force-fed three more full plates. I ended up passing out in the middle of a park a few blocks away, scuttling the rest of our afternoon plans.
Still, those extra-crispy potatoes: worth it.
Bringing it home
Back in the States, I've recreated the dish a number of times using slightly different methods each time, but the basics are always the same. First, get your hands on some new potatoes.
The Colombian varieties tend to be a little starchier with firmer skins than the new potatoes we can find 'round these parts, but really any potato will do. I vastly prefer smaller potatoes to larger ones—you get a better ratio of crust to flesh, letting you pop them into your mouth whole.
Next, put the potatoes in a pot, cover them with cold water, then add salt.
And I'm talking a lot of salt—I use about a half cup for a batch of potatoes. Whether that batch is a pound or four pounds, the amount of salt doesn't need to change much—in the end, the salt that goes into the serving bowl is only as much as clings to the potatoes after they come out of the pot. Still, you need enough in there to give yourself something to toss the potatoes with at the end.
Once the salt is in, bring the water to a boil and let the potatoes cook steadily, giving them a stir every once in a while, until the pan runs completely dry.
Once all that liquid is gone, let the potatoes rest for a few minutes. As they cool, you'll begin to see a hardened crystallized crust form on them, sort of like rock candy. Actually, I take that back. It's exactly like rock candy and forms in pretty much the same way.
The potatoes are fantastic as-is for salt lovers like me (and my wife), but I wondered if there were other ways to use this unique technique to appeal to other types of diners. A little experimenting was in order.
One of the simplest and most effective variations is to simply add some aromatics to the water as the potatoes cook. A couple of bay leaves, some fresh thyme or rosemary, or a few cloves of garlic all add flavor to the salt crust, giving you a potato with the same crystalline coating, but more layers of flavor.
Next I wondered if there was something more that the salty liquid was doing to the potatoes beyond just giving them a crust.
Crushing them reveals that the flesh inside is very dense and creamy—to my naked eye, more so than a plain old boiled or roasted potato, but just to be sure, I boiled two identical batches of potatoes, one in salted water and the other in plain water. Both were cooked until the water completely evaporated (this happened at about the same rate). Next I rinsed the excess salt crust off of the salty potatoes and compared them side-by-side.
The difference is pretty stark. Potatoes boiled in plain water retain 100% of their starting weight and unless you poke them, don't really look all that difference. Potatoes cooked in heavily salted water, on the other hand, lose a good 15% of their initial weight. This is presumably due to osmosis, the tendency of a solvent (in this case the potatoes' internal moisture) to travel across a membrane from an area of lower solute concentration (inside the potato) to an area of higher solute concentration (outside the potato).
The result is a potato that has a more intense potato flavor and denser, creamier texture (as opposed to the fluffier texture of plain boiled potatoes). The skin of salt-boiled potatoes also ends up thinner and more delicate. Even if you plan on rinsing off all the salt, I'd still suggest boiling potatoes using this method if more intense flavor is your goal.
Next I wondered what would happen if I subsequently roasted these delicate-skinned, wrinkly spuds. I tossed them with a bit of butter, threw them into a cast iron skillet, then parked them in a 400°F oven, tossing them every once in a while until they developed a golden appearance.
The result was the crispest whole-roasted new potatoes I'd ever tasted, with intensely potato-y centers.
I happened to have some extra herb butter lying around from testing out my Herb Butter-Roasted Spatchcock Turkey. It was flavored with sage, parsley, thyme, shallots, garlic, and chives—all flavors that would go pretty darn well with potatoes. It doesn't take a huge mental leap to see where this is going, does it?
I melted the herb butter in a little saucepan, tossed my salt-boiled and rinsed potatoes in it, then placed them on a rimmed baking sheet to roast.
I tossed them with a few more fresh herbs just as they come out of the oven to double up on that herb flavor.
For years now, my Ultra-Crispy Roast Potatoes have been a staple on my fall and winter table, but they just may have found a competitor for that coveted spot on the Thanksgiving spread.
I'm providing two recipes with this technique, one for the traditionalist (read: my wife), and the other for those who prefer the less salty, holiday-friendly, herb-crusted version.